fix: always run image scan so we can compare PRs

Author: jacdavi

.github/workflows/m365_image_build.yaml

@@ -128,9 +128,10 @@ jobs:
           exit 0
     outputs:
       image:  ${{ steps.build-and-push.outputs.image }}
-  m365-scan:
+  scan:
     name: Scan
-    if: github.ref == 'refs/heads/main'
+    # This condition prevents duplicate runs.
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
     permissions:
       security-events: write
     needs: build