Merge pull request #592 from sassoftware/add-gh-actions

adding github action to check shell code

.github/workflows/ci.yml

@@ -0,0 +1,17 @@
+name: checkshell
+on:
+  - pull_request
+jobs:
+  sh-checker:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Run the sh-checker
+        uses: luizm/action-sh-checker@master
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          SHELLCHECK_OPTS: -e SC1004 # exclude some shellcheck warnings.
+          SHFMT_OPTS: -s # arguments to shfmt.
+        with:
+          sh_checker_only_diff: true # only run against files that were updated
+          sh_checker_comment: true # include results as github comment