Enable more linting rules

[TimJentzsch]

Relevant issue: N/A

Description:

• Increase the line length from 88 to 100 (for both black and ruff). We have more than enough screen space to display 100 chars and it often makes the code look nicer and have less lines.
• Enable more doc lints that were disabled before. They are either formatting related and automatically fixable or just had one violation that I could easily fix. For example, the first doc line now starts consistently directly after the opening quotation marks, which is the convention recommended by Python.
• Enable the DTZ type of lints which enforce that we set a timezone for everything. This is important for the database and has caused errors before where we missed it. I disabled it for tests for now because there are a ton of violations.