fix: use latest as the label for master branch

Author: mayocream

.github/workflows/main.yml

@@ -55,6 +55,7 @@ jobs:
         uses: docker/metadata-action@v5
         with:
           images: ghcr.io/${{ github.repository }}/${{ matrix.image }}
+          tags: latest
 
       - name: Build and push
         uses: docker/build-push-action@v6