ci: publish Docker images to ghcr.io

Author: buchdag

.github/workflows/dockerhub.yml

@@ -36,6 +36,7 @@ jobs:
         uses: docker/metadata-action@v3
         with:
           images: |
+            ghcr.io/nginx-proxy/acme-companion
             nginxproxy/acme-companion
             jrcs/letsencrypt-nginx-proxy-companion
           tags: |
@@ -58,6 +59,13 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      
       - name: Build and push
         id: docker_build
         uses: docker/build-push-action@v2