Improve docker build+upload

[PGijsbers]

We currently have a script for automatically building and uploading a docker image. But it should be extended in the following ways:

• For each release, upload an image with a tag that matches the release (e.g., openml/openml-python:0.14.1).
• Match latest tag to the last stable release
• Have a default entrypoint that runs Python from an environment with openml-python installed
• Build cross-platform (support M1 mac without QEMU)
• Have the readme included on the docker page