Adding an auto-merger for dependabot updates (#1486)

.github/workflows/dependabot_auto_merge.yml

@@ -0,0 +1,38 @@
+---
+name: Dependabot auto-approval and auto-merge
+"on": pull_request
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'dependabot[bot]' }} # limit this to PRs opened by dependabot
+    steps:
+      - name: Dependabot metadata
+        id: metadata
+        uses: dependabot/fetch-metadata@v1
+        with:
+          github-token: "${{ secrets.GITHUB_TOKEN }}"
+          alert-lookup: true
+          compat-lookup: true
+      - uses: actions/checkout@v3
+      - name: Approve a PR if not already approved
+        run: |
+          # sets the upstream metadata for `gh pr status`
+          gh pr checkout "$PR_URL"
+          if [ "$(gh pr status --json reviewDecision -q .currentBranch.reviewDecision)" != "APPROVED" ];
+          then gh pr review --approve "$PR_URL"
+          else echo "PR already approved, skipping additional approvals to minimize emails/notification noise.";
+          fi
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
+      - name: Enable auto-merge for Dependabot PRs
+        if: ${{contains(steps.metadata.outputs.dependency-names, 'my-dependency') && steps.metadata.outputs.update-type == 'version-update:semver-patch'}}
+        run: gh pr merge --auto --merge "$PR_URL"
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}