Add Dependabot support for Git submodule updates

.github/dependabot.yml

@@ -30,3 +30,10 @@ updates:
       dev-dependencies:
         patterns:
           - "*"
+
+  - package-ecosystem: "gitsubmodule"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    labels:
+      - "submodule-update"

.github/workflows/dependabot-auto-merge.yml

@@ -0,0 +1,30 @@
+name: Dependabot auto-approve and merge
+on: pull_request
+
+permissions:
+  pull-requests: write
+  contents: write
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'dependabot[bot]' && contains(github.event.pull_request.labels.*.name, 'submodule-update') }}
+    steps:
+      - name: Dependabot metadata
+        id: metadata
+        uses: dependabot/fetch-metadata@v2
+        with:
+          github-token: "${{ secrets.GITHUB_TOKEN }}"
+
+      - name: Approve PR
+        run: gh pr review --approve "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Enable auto-merge for Dependabot PRs
+        if: ${{ steps.metadata.outputs.update-type != 'version-update:semver-major' }}
+        run: gh pr merge --auto --squash "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/dependabot-submodule-handler.yml

@@ -0,0 +1,97 @@
+name: Handle Dependabot Submodule Updates
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    paths:
+      - 'binding/voicevox_core'
+    branches:
+      - 'main'
+
+jobs:
+  update-hash:
+    if: ${{ github.actor == 'dependabot[bot]' && contains(github.event.pull_request.labels.*.name, 'submodule-update') }}
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - name: Generate a token
+        id: generate_token
+        uses: actions/create-github-app-token@v2
+        with:
+          app-id: ${{ secrets.APP_ID }}
+          private-key: ${{ secrets.APP_PRIVATE_KEY }}
+
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          token: ${{ steps.generate_token.outputs.token }}
+          submodules: recursive
+          ref: ${{ github.event.pull_request.head.ref }}
+          persist-credentials: false
+
+      - name: Setup Git
+        run: |
+          git config --global user.name "github-actions[bot]"
+          git config --global user.email "41898282+github-actions[bot]@users.noreply.github.com"
+
+      - name: Update commit hash
+        id: update-hash
+        run: |
+          # Get the updated commit hash from voicevox_core submodule
+          NEW_HASH=$(cd binding/voicevox_core && git rev-parse HEAD)
+
+          # Update the hash in the props file
+          sed -i.bak "s/<VoicevoxCoreCommitHash>.*<\/VoicevoxCoreCommitHash>/<VoicevoxCoreCommitHash>$NEW_HASH<\/VoicevoxCoreCommitHash>/" src/VoicevoxCoreSharp.Core/VoicevoxCoreSharp.Core.Metas.props
+
+          # Check if there are changes
+          if [[ $(git diff --name-only) != "" ]]; then
+            echo "Hash updated to $NEW_HASH"
+            echo "hash_updated=true" >> $GITHUB_OUTPUT
+          else
+            echo "No hash changes needed"
+            echo "hash_updated=false" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Setup Rust toolchain
+        uses: actions-rust-lang/[email protected]
+        if: ${{ steps.update-hash.outputs.hash_updated == 'true' }}
+
+      - name: Generate bindings
+        if: ${{ steps.update-hash.outputs.hash_updated == 'true' }}
+        working-directory: ./binding
+        run: make generate
+
+      - name: Check for code generation changes
+        id: binding-diff
+        if: ${{ steps.update-hash.outputs.hash_updated == 'true' }}
+        run: |
+          if [[ $(git diff --name-only | grep .cs$) != "" ]]; then
+            echo "binding_has_update=true" >> $GITHUB_OUTPUT
+            echo "Code generation changes detected. Manual review required."
+          else
+            echo "binding_has_update=false" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Commit changes
+        if: ${{ steps.update-hash.outputs.hash_updated == 'true' && steps.binding-diff.outputs.binding_has_update != 'true' }}
+        run: |
+          git add src/VoicevoxCoreSharp.Core/VoicevoxCoreSharp.Core.Metas.props
+          git commit -m "Update VoicevoxCore commit hash"
+          git config --global url."https://x-access-token:${{ steps.generate_token.outputs.token }}@github.com".insteadOf "https://github.com"
+          git push
+
+      - name: Comment on PR if binding updates needed
+        if: ${{ steps.binding-diff.outputs.binding_has_update == 'true' }}
+        env:
+          GH_TOKEN: ${{ steps.generate_token.outputs.token }}
+        run: |
+          gh pr comment ${{ github.event.pull_request.number }} --body "⚠️ This submodule update requires manual code generation changes. Please review the changes and update accordingly."
+          exit 1
+
+      - name: Comment on PR if hash updated
+        if: ${{ steps.update-hash.outputs.hash_updated == 'true' && steps.binding-diff.outputs.binding_has_update != 'true' }}
+        env:
+          GH_TOKEN: ${{ steps.generate_token.outputs.token }}
+        run: |
+          gh pr comment ${{ github.event.pull_request.number }} --body "✅ Successfully updated VoicevoxCore commit hash to \`$NEW_HASH\`"