ci: auto-merge Dependabot patch/minor PRs

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

@@ -0,0 +1,32 @@
+name: Dependabot auto-merge
+
+# Auto-enable squash-merge on Dependabot PRs for patch and minor updates.
+# Major bumps are left for human review (potential breaking changes).
+#
+# Auto-merge waits for the required status checks defined in branch
+# protection (test 3.12 / test 3.13 / drift-check); GitHub will not
+# merge until they pass.
+
+on: pull_request
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  auto-merge:
+    if: github.actor == 'dependabot[bot]'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Fetch Dependabot metadata
+        id: meta
+        uses: dependabot/fetch-metadata@08eff52bf64351f401fb50d4972fa95b9f2c2d1b  # v2.4.0
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Enable auto-merge for patch / minor updates
+        if: steps.meta.outputs.update-type == 'version-update:semver-patch' || steps.meta.outputs.update-type == 'version-update:semver-minor'
+        run: gh pr merge --auto --squash "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}