Update docker-image.yml

* change from checkout to docker/build-push-action

Author: schenkd

.github/workflows/docker-image.yml

@@ -9,8 +9,9 @@ jobs:
  runs-on: ubuntu-latest
  steps:
  - name: Build the Docker image
- uses: actions/checkout@v2
+ uses: docker/build-push-action@v1.1.0
  with:
  username: ${{ secrets.DOCKER_USERNAME }}
  password: ${{ secrets.DOCKER_PASSWORD }}
+ repository: schenkd/nginx-ui
  tag_with_ref: true