Add action check to auto-merge workflow

- Ensure workflow only runs when review is submitted (not dismissed or other events)
- Add github.event.action == 'submitted' check for better event filtering

Co-authored-by: thomasturrell <1552612+thomasturrell@users.noreply.github.com>

Author: Copilot

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

@@ -9,7 +9,7 @@ permissions:
 jobs:
   auto-merge:
     runs-on: ubuntu-latest
-    if: github.event.review.state == 'approved' && github.event.pull_request.user.login == 'dependabot[bot]'
+    if: github.event.action == 'submitted' && github.event.review.state == 'approved' && github.event.pull_request.user.login == 'dependabot[bot]'
     steps:
       - name: Get Dependabot metadata
         id: metadata