CI: fix invalid variable warning

.github/workflows/docker-image.yml

@@ -31,7 +31,6 @@ jobs:
         uses: docker/build-push-action@v2
         with:
           context: .
-          github_token: ${{ secrets.GITHUB_TOKEN }}
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}