ci: add main tag to Docker image

Author: lalver1

.github/workflows/docker-publish.yml

@@ -83,6 +83,7 @@ jobs:
           file: Dockerfile
           push: true
           tags: |
+            ghcr.io/${{ github.repository }}:${{ github.ref_name }}
             ghcr.io/${{ github.repository }}:${{ github.sha }}
 
       - name: Deploy to MST Azure Web App