Should notebooks be tested within the CI pipeline, so there are kept up to date? #331

Inspired by #325 (comment).

The repository contains a number of notebooks that can function as examples on how to use the repository. Many/most/all (?) of these are not maintained and outdated. I have refrained from putting effort into them, because there is a chance they will be outdated soon-ish anyway.

I have a proposition that would increase the quality and usefulness of these notebooks.

1. We make a GitHub actions that runs the notebooks when a PR is created. This ensures that the PR does not break the functioning of the notebooks.
2. We make an example notebook for all/most features of the repo. These can be taken from existing projects or purpose-built.
3. We add these examples to the documentation as basic and intermediate/advanced examples.

This issue relies on #330 to be completed first.

What do you think, @JulietteFrancovich @DaniBodor?