Improve CI

[schmoelder]

Currently, we use pre-commit/pre-push hooks to create different branches that

• reset --hard on dev
• Create ipynbs for
• Remove cells with solution tags for teaching branch
• Run all notebooks for solution branch

However, this takes too long and is error prone since it can lead to issues with the local files. Instead, we should add some GitHub Actions that do that for us.

Open Question:

• protect multiple branches on GitHub?

[ronald-jaepel]

I've created a CI github action in the test-ci branch.

So far it seems to work.
Open question 2:

• the figures do not show up in the ipynbs. Should add an automatic replacement with jupyter syntax to show the images?