Add registry specification for GHCR login

Author: shuesken

.github/workflows/docker-build.yml

@@ -17,6 +17,7 @@ jobs:
     - name: Log in to GHCR
       uses: docker/login-action@v2
       with:
+        registry: ghcr.io
         username: ${{ github.actor }}
         password: ${{ secrets.GITHUB_TOKEN }}