Fixed CI script for PRs

Author: GNimrodG

.github/workflows/build-frontend.yml

@@ -26,8 +26,8 @@ jobs:
         id: meta
         uses: docker/metadata-action@v5
         with:
-          # list of Docker images to use as base name for tags
-          images: ${{ vars.DOCKER_REGISTRY_URL }}/smo-frontend
+          # Dynamic image name: if DOCKER_REGISTRY_URL is set use <registry>/smo-frontend, otherwise just 'smo-frontend'
+          images: ${{ vars.DOCKER_REGISTRY_URL && format('{0}/smo-frontend', vars.DOCKER_REGISTRY_URL) || 'smo-frontend' }}
           # generate Docker tags based on the following events/attributes
           tags: |
             type=ref,event=branch