Split auto-merge job into its own action

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

@@ -0,0 +1,23 @@
+# Dependabot Auto Merge
+#
+# This Action will automatically merge Pull Requests created by Dependabot.
+name: 'Dependency review'
+on:
+  pull_request:
+    branches: [ "main" ]
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  dependency-auto-merge:
+    name: 'Auto merge Dependabot updates'
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'dependabot[bot]' }}
+
+    steps:
+      - uses: fastify/github-action-merge-dependabot@v3
+        with:
+          use-github-auto-merge: true
+

.github/workflows/dependency-review.yml

@@ -60,23 +60,3 @@ jobs:
         #   deny-licenses: GPL-1.0-or-later, LGPL-2.0-or-later
         #   retry-on-snapshot-warnings: true
 
-  dependency-auto-merge:
-    name: 'Auto merge (Dependabot PR)'
-    runs-on: ubuntu-latest
-    needs: [dependency-submission, dependency-review]
-    if: ${{ github.actor == 'dependabot[bot]' && github.event_name == 'pull_request' }}
-
-    steps:
-      - name: Fetch metadata
-        id: metadata
-        uses: dependabot/[email protected]
-        with:
-          github-token: '${{ secrets.GITHUB_TOKEN }}'
-
-      - name: Enable auto-merge
-        id: auto-merge
-        run: gh pr merge --auto --merge "$PR_URL"
-        env:
-          PR_URL: ${{ github.event.pull_request.html_url }}
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-