Task: Fix linting & and pre-commit-hooks and add to CI workflow #3217

Motivation:
Pre-commit hooks and proper linting has not been applied consistently in existing codebase. Following DeepLabCut/DeepLabCut-live#165 by @C-Achard, it would be great to introduce a modern and consistent linting configuration again, after reformatting the codebase. This enforces consistent style, which makes code easier to read, review, and maintain and can help to catch mistakes early before they turn into bugs (with very low effort).

Related PRs
The following PRs have been opened to address this. They should be merged in a specific order:

• 1. First merge Install through pyproject.toml (PEP 518/621) #3184, which introduces a modern pyproject.toml
• 2. Then merge PR Update pre-commit & linting configuration #3215 , to update the linting configuration in the pyproject.toml and the pre-commit hooks.
• 3. Merge PR Apply linting to entire codebase & add CI workflow to check linting #3216, which reformats the entire codebase and adds linting to the CI workflows.