Add automerge script for dependabot

Signed-off-by: Heinz N. Gies <[email protected]>

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

@@ -0,0 +1,25 @@
+name: Dependabot auto-merge
+
+on:
+  pull_request_target:
+
+permissions:
+  pull-requests: write
+  contents: write
+
+jobs:
+  auto-merge:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'dependabot[bot]' }}
+    steps:
+      - name: Approve a PR
+        run: gh pr review --approve "$PR_URL"
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GITHUB_TOKEN: ${{secrets.PAT_TOKEN}}
+      - name: Enable auto-merge for Dependabot PRs
+        run: gh pr merge --auto --rebase "$PR_URL"
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GITHUB_TOKEN: ${{secrets.BOT_TOKEN}}
+