Adding isort

[florianjehn]

isort makes that all imports are ordered the same way throughout our code: https://pycqa.github.io/isort/

It would be great if this would simply run for every commit pushed to the repository.

Was not able to get it to work with GIthub Actions and help would be appreciated.

[lukaszgajewski]

It seems that it's not supported by the github action we use: wearerequired/lint-action#356
There is a fork we could consider: https://github.com/Gobot1234/lint-action or add it ourselves: https://github.com/wearerequired/lint-action/blob/master/CONTRIBUTING.md#adding-a-new-linter.

[florianjehn]

Like the other issue, not really important, but if you think you can fix this without much effort feel free to send a pull request.