Add tags to docker images to prevent branches from overwriting Parastell docker images

[bquan0]

Currently, docker_publish.yml pulls and pushes docker images to a hardcoded image name and tag, which is the official parastell docker image. This can be problematic if a branch changes something and pushes a docker image that doesn't work.

I have changed docker_publish.yml to now pull and push docker images to the same image name, but with a tag based on the branch name if the branch is not main. This way, contributors can make changes without worrying about breaking the official image.

This PR is a continuation of #154, with the difference being that this PR was pushed to a branch in the repo owned by svalinn instead of a branch in my forked repo.

[bquan0]

The workflows have passed, and there are now new docker-build-tweak tags for the parastell image and the parastell-ci image (since that's the name of this branch). The Test CI Image workflow run also uses the image with the correct tag.

Let me know if I should change the tag name generation.

[gonuke]

Thanks @bquan0