Change/split test settings setup

[afuetterer]

Rationale / Begründung

Can the test settings testing/config/settings be set up differently? It is a little difficult to wrap your head around the settings setup.

Affected

Tests.

Minimal functionality

I propose the following setup:

• base settings
• dev settings for local development
• testing settings for running the unit tests

Remove the mysql, postgres, sqlite modules and choose the database backend from an env variable.

What do you think?

References / Verweise

Similar to:

• Update the rdmo-app to use split settings and environment variables. rdmo-app#11

[jochenklar]

Hey @afuetterer , I updated the settings to make them similar to the new rdmo-app (with an identical testing/config/settings/__init__.py) and put the database config in testing/config/settings/base.py based on a environment variable GITHUB_DB_BACKEND.