Now that #140 is closed, I would still like to tackle the rest of the build system in this repo (low priority). To me, the next point to resolve would be the automated testing on the CI. Currently, we are using the "old" development-dependencies to build and run tests on PR, see here. It would be great if we can move away from this and use the same Dockerfile that the CI now uses to build the image.

The main disadvantage of this Dockerfile is that it takes long to build with the dependencies so we need a caching functionality.

@LouisBrunner what are your thoughts on this? any suggestions on what actions we could use to have the "lightest" CI possible.