Add Dependabot auto-merge workflow

Signed-off-by: Mathias L. Baumann <[email protected]>

Author: Marenz

.github/workflows/auto-dependabot.yaml

@@ -0,0 +1,15 @@
+name: Auto-merge Dependabot PRs
+
+on:
+  pull_request:
+
+jobs:
+  auto-merge:
+    if: github.actor == 'dependabot[bot]'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Auto-merge Dependabot PR
+        uses: ad/dependabot-auto-approve@v1
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          merge-method: 'merge'