Restore conditional checkout in image scan workflow

Author: dash14

.github/workflows/image-scan.yml

@@ -16,6 +16,7 @@ jobs:
 
     steps:
       - name: Checkout
+        if: github.event_name == 'workflow_dispatch'
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           persist-credentials: false