Only tag images built on main as latest

Author: Scott Davidson

.github/workflows/docker-build-push-web-container-on-tag.yml

@@ -38,7 +38,7 @@ jobs:
           images: ${{ env.REGISTRY_IMAGE }}
           tags: |
             type=raw,value=${{ env.REGISTRY_IMAGE }}:${{ github.ref_name }}
-            type=raw,value=${{ env.LATEST_TAG == 'true' && format('{0}:latest', env.REGISTRY_IMAGE) || '' }}
+            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/main' }}
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3