Use repository_owner instead of actor

Co-authored-by: Copilot <[email protected]>

Author: PythonGermany

.github/workflows/docker-cd.yml

@@ -37,7 +37,7 @@ jobs:
         uses: docker/login-action@v3
         with:
           registry: ${{ env.REGISTRY }}
-          username: ${{ github.actor }}
+          username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
       # Set up BuildKit Docker container builder to be able to build