Go through the code looking for improvements that can be made when abandoning Python 2.x.

[CSchoel]

By dropping support for Python 2.x, we can modernize the codebase and get rid of from __future__ import and other hacks.

• [ ] Check where we do from __future__ import, removing all those instances and simplifying the codebase accordingly.
• [ ] Run pyupgrade over the codebase.
• [ ] Check with Ruff if there are any outdated parts in the codebase left.
• [ ] Check that the unit tests still run after all changes.