Deployment of documentation on merge

[wreise]

Reference issues/PRs
Continuation of #383 , updated with the latest state of the docs pipeline.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description
Add a step to automatically publish docs on merge.

Screenshots (if appropriate)

Any other comments?

Checklist

• I have read the guidelines for contributing.
• My code follows the code style of this project. I used flake8 to check my Python changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed. I used pytest to check this on Python tests.

[wreise]

I think it would greatly help if we kept the list of versions up to date, so as we just aways run update-versions, without updating the list itself in the deployment process. We already did that for the last releases, so I suggest to keep it that way.

Regarding notebooks, I get some errors in the MNIST, which i do not locally. It also makes me think whether we could publish the artifacts from the notebook tests, instead of doing running them again.