Add a ci-update-workflow GitHub Actions to update the go-version matr…

…ix (#307)

Signed-off-by: Chi Zhang <chizhg@google.com>

.github/workflows/ci-update-workflow.yml

@@ -0,0 +1,68 @@
+name: ci-update-workflow
+
+on:
+  schedule:
+  # Run every day at 10AM.
+  - cron: '0 10 * * *'
+
+jobs:
+  update-go-versions:
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write # Enable OIDC
+    steps:
+    - id: 'auth'
+      uses: 'google-github-actions/auth@v1'
+      with:
+        credentials_json: '${{ secrets.GCP_CREDENTIALS }}'
+
+    - name: 'Set up Cloud SDK'
+      uses: 'google-github-actions/setup-gcloud@v1'
+
+    - name: Get available Go versions
+      run: |
+        # Get all supported Go versions and pass the space-separated versions
+        # string to the next step
+        versions=$(gcloud functions runtimes list --format="value(NAME)" --project=gae-runtimes-private --region=us-west1 | grep ^go | tr '\n' ' ' | xargs)
+        echo "::set-output name=versions::$versions"
+      id: get_versions
+
+    - name: Checkout appengine repo
+      uses: actions/checkout@v2
+
+    # Sign the commit.
+    # https://www.chainguard.dev/unchained/keyless-git-commit-signing-with-gitsign-and-github-actions
+    - uses: chainguard-dev/actions/setup-gitsign@main
+
+    - name: Update Go versions
+      run: |
+        readarray -d ' ' -t versions <<< "${{ steps.get_versions.outputs.versions }}"
+        
+        versions_str=""
+        for version in "${versions[@]}"; do
+          major=${version:2:1}
+          minor=${version:3:2}
+          versions_str+="'$major.$minor.x', "
+        done
+        # Remove the last comma and space
+        versions_str=${versions_str%, *}
+
+        # Only replace the first occurance
+        sed -i "0,/^        go-version: \[.*/s//        go-version: \[$versions_str\]/" .github/workflows/ci-v2.yaml
+  
+    - name: Create Pull Request
+      uses: peter-evans/create-pull-request@v4
+      with:
+        token: ${{ secrets.GITHUB_TOKEN }}
+        commit-message: Update go-version matrix
+        title: Update go-version matrix
+        body: |
+          - go-version matrix updates
+
+          Update the go-version matrix in the CI workflows to include the new supported runtimes.
+ 
+          Auto-generated by [create-pull-request][1]
+
+          [1]: https://github.com/peter-evans/create-pull-request
+        branch: update-go-version-matrix
+        reviewers: jinglundong