chore(ci): auto-merge Dependabot patch/minor PRs

Author: bagelbits

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

@@ -0,0 +1,27 @@
+name: Dependabot auto-merge
+
+on: pull_request_target
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  auto-merge:
+    if: github.event.pull_request.user.login == 'dependabot[bot]'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Fetch Dependabot metadata
+        id: meta
+        uses: dependabot/fetch-metadata@25dd0e34f4fe68f24cc83900b1fe3fe149efef98 # v3.1.0
+
+      - name: Approve and enable auto-merge (patch/minor only)
+        if: steps.meta.outputs.update-type != 'version-update:semver-major'
+        run: |
+          gh pr review --approve "$PR_URL"
+          gh pr merge --auto --squash "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          # PAT owned by a code owner (@bagelbits) — approves as you to satisfy
+          # the code-owner review gate. GITHUB_TOKEN and App tokens cannot.
+          GH_TOKEN: ${{ secrets.DEPENDABOT_AUTOMERGE_TOKEN }}