Technical - Move linting tests to their own test suite

[Fancien]

Is your feature request related to a problem? Please describe.

At the moment, the linting run in the same test suite as pytest, meaning that they need the docker image to be up and running.

Describe the solution requested

It would be more efficient to run the linting in a separate test suite. This would avoid building the docker image.

Describe possible alternatives

Another alternative would be to put the linting test before the image building step in the test suite, but a consequence of that is that the unittests would not run if black or flake8 report an issue.

Other info context

The impacted file would be the main.yml in the github workflows.