Automatic notebook testing

Given that we now have solutions to all the notebooks (https://gitlab.ewi.tudelft.nl/mmc-tudelft/education/MMSRNotebooks/-/issues/9) we should introduce notebook testing.

The main idea is that whenever we introduce a change to a notebook we would like to run it under all likely environments (e.g. Colab, VM, Docker etc) to make sure that the notebook outputs match what we expect/latest commit didn't break anything.

The main difficulty is replicating the Colab environment with all of its binaries/packages. Unfortunately, Colab team have not released their Docker image. Whilst it may happen eventually, currently the only way that comes to mind is to connect Colab to a local runtime (https://research.google.com/colaboratory/local-runtimes.html). Further examination is needed but a potential source of conflict will also be the fact that we would have to make sure that the testing is able to interact with/use local files, not those on Colab.

Running testing code on VM is easier but we also introduce a split between Colab and local infrastructure. Again, Docker containers for everything would be ideal but this is currently not possible.

We should decide on whether this issue is a priority after we rule on unifying colab and VM notebooks as well as our transition to Docker.