Add Dependabot auto-merge workflow (#6)

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

@@ -0,0 +1,27 @@
+name: Dependabot Auto-Merge
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+  workflow_call: {}
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  auto-merge:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Fetch Dependabot metadata
+        if: github.actor == 'dependabot[bot]'
+        uses: dependabot/fetch-metadata@v2
+        id: metadata
+
+      - name: Enable auto-merge for non-major updates
+        if: github.actor == 'dependabot[bot]' && steps.metadata.outputs.update-type != 'version-update:semver-major'
+        run: gh pr merge --auto --squash "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          GH_TOKEN: ${{ github.token }}