Specifies default branch rather than main

Author: Blaize Kaye

.github/workflows/insights-trivy-image.yaml

@@ -78,7 +78,7 @@ jobs:
             # set edge tag for default branch
             type=edge,enable={{is_default_branch}}
             # set latest tag for main branch - this is required for the scheduled builds
-            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/main' }}
+            type=raw,value=latest,enable=${{is_default_branch}}
             # set tag+build for default branch
             type=raw,value=${{ env.DOCKER_TAG}},enable={{is_default_branch}}
             # tag event