Do not push to registry on PRs

Author: octeep

.github/workflows/container.yml

@@ -68,4 +68,4 @@ jobs:
             --label "org.opencontainers.image.created=$(date -u --rfc-3339=seconds)" \
             --cache-from type=gha \
             --cache-to type=gha,mode=max \
-            --pull --push .
+            --pull ${{ github.event_name == 'push' && '--push' || '' }} .