GH Actions: "pin" all action runners

Recently there has been more and more focus on securing GH Actions workflows - in part due to some incidents.

The problem with "unpinned" action runners is as follows:
* Tags are mutable, which means that a tag could point to a safe commit today, but to a malicious commit tomorrow.
    Note that GitHub is currently beta-testing a new "immutable releases" feature (= tags and release artifacts can not be changed anymore once the release is published), but whether that has much effect depends on the ecosystem of the packages using the feature.
    Aside from that, it will likely take years before all projects adopt _immutable releases_.
* Action runners often don't even point to a tag, but to a branch, making the used action runner a moving target.
    _Note: this type of "floating major" for action runners used to be promoted as good practice when the ecosystem was "young". Insights have since changed._

While it is convenient to use "floating majors" of action runners, as this means you only need to update the workflows on a new major release of the action runner, the price is higher risk of malicious code being executed in workflows.

Dependabot, by now, can automatically submit PRs to update pinned action runners too, as long as the commit-hash pinned runner is followed by a comment listing the released version the commit is pointing to.

So, what with Dependabot being capable of updating workflows with pinned action runners, I believe it is time to update the workflows to the _current_ best practice of using commit-hash pinned action runners.

The downside of this change is that there will be more frequent Dependabot PRs.

If this would become a burden/irritating, the following mitigations can be implemented:
1. Updating the Dependabot config to group updates instead of sending individual PRs per action runner.
2. A workflow to automatically merge Dependabot PRs as long as CI passes.

Ref: https://docs.github.com/en/actions/reference/security/secure-use#using-third-party-actions

Author: jrfnl

.github/workflows/basic-qa.yml

@@ -30,17 +30,17 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - name: Restore lychee cache
-        uses: actions/cache@v4
+        uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
         with:
           path: .lycheecache
           key: cache-lychee-${{ github.sha }}
           restore-keys: cache-lychee-
 
       - name: Link Checker
-        uses: lycheeverse/lychee-action@v2
+        uses: lycheeverse/lychee-action@885c65f3dc543b57c898c8099f4e08c8afd178a2 # v2.6.1
         with:
           # Sidebar file exclusion is needed to work-around an upstream bug.
           # Should be removed once bug https://github.com/lycheeverse/lychee/issues/1788 has been fixed.
@@ -57,10 +57,10 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - name: Spellcheck
-        uses: streetsidesoftware/cspell-action@v7
+        uses: streetsidesoftware/cspell-action@dcd03dc3e8a59ec2e360d0c62db517baa0b4bb6d # v7.2.0
         with:
           # Define glob patterns to filter the files to be checked. Use a new line between patterns to define multiple patterns.
           files: '**/*.md'
@@ -80,14 +80,14 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - name: Set up problem matcher
-        uses: lumaxis/shellcheck-problem-matchers@v2
+        uses: lumaxis/shellcheck-problem-matchers@b02a1715a00c729b20eed3ebb7edf56fa9a433ba # v2.1.0
         with:
           format: gcc
 
       - name: Run ShellCheck
-        uses: ludeeus/[email protected]
+        uses: ludeeus/action-shellcheck@00cae500b08a931fb5698e11e79bfbd38e612a38 # 2.0.0
         with:
           format: gcc

.github/workflows/label-merge-conflicts.yml

@@ -21,7 +21,7 @@ jobs:
 
     steps:
       - name: Check PRs for merge conflicts
-        uses: eps1lon/actions-label-merge-conflict@v3
+        uses: eps1lon/actions-label-merge-conflict@1df065ebe6e3310545d4f4c4e862e43bdca146f0 # v3.0.3
         with:
           dirtyLabel: "Status: has merge conflict"
           repoToken: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/label-new-prs.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
       - name: Label new PRs
-        uses: srvaroa/labeler@v1
+        uses: srvaroa/labeler@9c29ad1ef33d169f9ef33c52722faf47a566bcf3 # v1
         env:
           GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
 
@@ -38,10 +38,10 @@ jobs:
     steps:
       # Checkout is needed to use the `use_local_config` option.
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - name: Verify changes to the labeling logic
-        uses: srvaroa/labeler@v1
+        uses: srvaroa/labeler@9c29ad1ef33d169f9ef33c52722faf47a566bcf3 # v1
         with:
           use_local_config: true
           fail_on_error: true

.github/workflows/label-remove-outdated.yml

@@ -18,7 +18,7 @@ jobs:
     name: Clean up labels on issue close
 
     steps:
-      - uses: mondeja/remove-labels-gh-action@v2
+      - uses: mondeja/remove-labels-gh-action@b7118e4ba5dca74acf1059b3cb7660378ff9ab1a # v2.0.0
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           labels: |
@@ -35,7 +35,7 @@ jobs:
     name: "Clean up labels on PR (re-)review request"
 
     steps:
-      - uses: mondeja/remove-labels-gh-action@v2
+      - uses: mondeja/remove-labels-gh-action@b7118e4ba5dca74acf1059b3cb7660378ff9ab1a # v2.0.0
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           labels: |
@@ -48,7 +48,7 @@ jobs:
     name: Clean up labels on PR merge
 
     steps:
-      - uses: mondeja/remove-labels-gh-action@v2
+      - uses: mondeja/remove-labels-gh-action@b7118e4ba5dca74acf1059b3cb7660378ff9ab1a # v2.0.0
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           labels: |
@@ -68,7 +68,7 @@ jobs:
     name: Clean up labels on PR close
 
     steps:
-      - uses: mondeja/remove-labels-gh-action@v2
+      - uses: mondeja/remove-labels-gh-action@b7118e4ba5dca74acf1059b3cb7660378ff9ab1a # v2.0.0
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           labels: |

.github/workflows/pr-comment.yml

@@ -29,7 +29,7 @@ jobs:
 
     steps:
       - name: Download PR info artifact
-        uses: actions/github-script@v8
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         with:
           script: |
             const allArtifacts = await github.rest.actions.listWorkflowRunArtifacts({
@@ -75,7 +75,7 @@ jobs:
           echo "URL=$value" >> "$GITHUB_OUTPUT"
 
       - name: "Post comment to review artifact"
-        uses: mshick/add-pr-comment@v2
+        uses: mshick/add-pr-comment@b8f338c590a895d50bcbfa6c5859251edc8952fc # v2.8.2
         with:
           issue: ${{ steps.pr_number.outputs.PR_NR }}
           repo-token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/publish-wiki.yml

@@ -43,10 +43,10 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - name: Install PHP
-        uses: shivammathur/setup-php@v2
+        uses: shivammathur/setup-php@ec406be512d7077f68eed36e63f4d91bc006edc4 # 2.35.4
         with:
           php-version: 'latest'
           ini-values: error_reporting=-1, display_errors=On, display_startup_errors=On, log_errors_max_len=0
@@ -119,7 +119,7 @@ jobs:
       - name: "[PR only] Upload the preprocessed wiki files as an artifact"
         if: ${{ github.event_name == 'pull_request' }}
         id: artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: wiki-files
           path: ./_wiki
@@ -132,13 +132,13 @@ jobs:
       # ################################################################################
 
       - name: Check GitHub Git Operations status
-        uses: crazy-max/ghaction-github-status@v4
+        uses: crazy-max/ghaction-github-status@fa6ac37620bc5d44b93e15caed498629665e9ff5 # v4.2.0
         with:
           git_threshold: partial_outage
 
       - name: Deploy to wiki
         if: ${{ github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository }}
-        uses: Andrew-Chen-Wang/[email protected]
+        uses: Andrew-Chen-Wang/github-wiki-action@2c80c13ee98aa43683bd77973ef4916e2eedf817 # v5.0.1
         env:
           COMMIT_MSG: ${{ github.event.head_commit.message }}
           DEFAULT_COMMIT_MSG: "Update wiki ${{ github.sha }}"
@@ -175,7 +175,7 @@ jobs:
 
       - name: Upload PR info as artifact
         if: ${{ github.event_name == 'pull_request' }}
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: pr_info
           path: pr/