fix: try https:// prefix for cross-Gitea action

.gitea/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - uses: git.librete.ch/libretech/actions/.gitea/actions/docker-build@main
+      - uses: https://git.librete.ch/libretech/actions/.gitea/actions/docker-build@main
         with:
           registry: ${{ secrets.REGISTRY }}
           registry_user: ${{ secrets.REGISTRY_USER }}