Use existing registry user secret

.github/workflows/docker-build.yml

@@ -46,17 +46,17 @@ jobs:
 
       - name: Log in to package registry
         env:
-          REGISTRY_USERNAME: ${{ secrets.REGISTRY_USERNAME }}
+          REGISTRY_USER: ${{ secrets.REGISTRY_USER }}
           REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
         run: |
-          if [ -z "$REGISTRY_USERNAME" ] || [ -z "$REGISTRY_TOKEN" ]; then
+          if [ -z "$REGISTRY_USER" ] || [ -z "$REGISTRY_TOKEN" ]; then
             echo "Missing registry credentials."
-            echo "Create repository secrets REGISTRY_USERNAME and REGISTRY_TOKEN."
+            echo "Create repository secrets REGISTRY_USER and REGISTRY_TOKEN."
             echo "REGISTRY_TOKEN must be a Gitea access token with package write permission."
             exit 1
           fi
 
-          echo "$REGISTRY_TOKEN" | docker login "$REGISTRY" -u "$REGISTRY_USERNAME" --password-stdin
+          echo "$REGISTRY_TOKEN" | docker login "$REGISTRY" -u "$REGISTRY_USER" --password-stdin
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3