automate tests in github actions

[tkv29]

Description:
This tasks inlcudes the automation of current and future tests in github actions.

Acceptance Criteria

• for every commit the tests should be executed
• the tests should executed before the linter

[PitButtchereit]

The tests that we currently run also execute the modules. Therefore an API Call is needed. I have looked into how this can be done with Github Actions. Since Github needs to know an API Key I could not implement it easily.

Automating deterministic tests or using mock objects should be easily possible since the name change of the root directory allows us to execute the tests from the command line with python manage.py test <app name>.