Publish Docker image

[jd1]

I really like what this action does and it helps me a lot to prevent bad CSS.

But with every pipeline run the building of the docker container takes around 20 seconds. Running the linter takes only 4 seconds. This is really annoying.

As far as I know, it should be possible to publish the Docker image, e.g. on ghcr.io so that the pipeline can download the image and run it.