approve if the PR branch belongs to dependabot

.github/workflows/auto-dependabot.yml

@@ -27,7 +27,7 @@ jobs:
   # Pull request Auto merge is not enabled for this repository
   dependabot:
     runs-on: ubuntu-latest
-    if: github.event.pull_request.user.login == 'dependabot[bot]'
+    if: startsWith(github.head_ref, 'dependabot/')
     steps:
       - name: Dependabot metadata
         id: metadata