chore: target PR author for dependabot check, not actor

Author: smlx

.github/workflows/dependabot-automerge.yaml

@@ -11,7 +11,7 @@ jobs:
       contents: write
       pull-requests: write
     runs-on: ubuntu-latest
-    if: github.actor == 'dependabot[bot]'
+    if: github.event.pull_request.user.login == 'dependabot[bot]'
     steps:
     - name: Fetch dependabot metadata
       id: metadata