Add linter to our workflow.

[CendioZeijlon]

Right now, we aren't checking for simple syntax errors when we run our tests.

Such errors should optimally be found when running the unittests. But if the tests do not reach a specific code path for some reason, a lint check should serve as a good sanity check of the state of the code.

[notypecheck]

@ThinLinc-Zeijlon Would you want to migrate to a package manager (e.g. uv) as well?
Most "modern" tool combination would look something like this:

• Package Manager: uv
• Linter/Formatter: ruff
• Type Checker: mypy/pyright
• Dependency Linter: deptry (this tool could check if your dependencies are used incorrectly, e.g. a dev dependency imported inside of your sources, or is simply not used)
• Test Runner: pytest