Add dependabot auto-merge action (#7127)

* add dependabot action

* accept all version updates on success

* fix braces

* fix token name

.github/workflows/dependabot-automerge.yml

@@ -0,0 +1,24 @@
+name: Dependabot auto-merge
+on:
+  workflow_run:
+    workflows: [ "build" ]
+    types:
+      - completed
+permissions:
+  pull-requests: write
+  contents: write
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'dependabot[bot]' && github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success' }}
+    steps:
+      - name: Dependabot metadata
+        id: metadata
+        uses: dependabot/[email protected]
+        with:
+          github-token: "${{ secrets.GITHUB_TOKEN }}"
+      - name: Enable auto-merge for Dependabot PRs
+        run: gh pr merge --auto --merge "$PR_URL"
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}