chore: push code-server image to GHCR (#5187)

.github/workflows/docker.yaml

@@ -35,6 +35,13 @@ jobs:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
 
+      - name: Login to GHCR
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Get version
         id: version
         run: echo "::set-output name=version::$(jq -r .version package.json)"