update Docker container offerings

[tomkralidis]

Currently, pygeoapi produces Docker images via GitHub Actions to the following container registries:

• Docker Hub (on release, and latest based on master branch)
• GitHub Container Registry (latest based on master branch)

Currently, the latest image is ~1.5GB containing numerous optional dependencies. It would be valuable to offer various images based on different deployment profiles/environments.

• determine images to produce (e.g. slim, default, full)
• add/update Dockerfile setups accordingly
• update GitHub Action for container publication
• update documentation

cc @justb4 @francbartoli @webb-ben @ricardogsilva

[github-actions]

This Issue has been inactive for 90 days. As per RFC4, in order to manage maintenance burden, it will be automatically closed in 7 days.

[kalxas]

I have been experimenting with a slim version of our Docker image. I agree it would be good to have different images for different use cases.