ci: auto-merge dependabot patch update PRs (#431)

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

@@ -0,0 +1,26 @@
+# Copied from GitHub docs:
+# https://docs.github.com/en/code-security/supply-chain-security/keeping-your-dependencies-updated-automatically/automating-dependabot-with-github-actions#enable-auto-merge-on-a-pull-request
+
+name: Dependabot auto-merge
+on: pull_request
+
+permissions:
+  pull-requests: write
+  contents: write
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'dependabot[bot]' }}
+    steps:
+      - name: Dependabot metadata
+        id: metadata
+        uses: dependabot/fetch-metadata@v1.1.1
+        with:
+          github-token: "${{ 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}}