This PR is part of the task described in issue #3217

Motivation:

Pre-commit hooks and proper linting has not been applied consistently in existing codebase. Following DeepLabCut/DeepLabCut-live#165, it would be great to introduce a modern and consistent linting configuration again, after reformatting the codebase.

Order of merging:

• 1. First merge Install through pyproject.toml (PEP 518/621) #3184, which introduces a modern pyproject.toml
• 2. Then merge the current PR, to update the linting configuration in the pyproject.toml and the pre-commit hooks.
  edit: merging this PR into PR Apply linting to entire codebase & add CI workflow to check linting #3216, since it requires simultaneous introduction in the main branch.
• 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.

Current ruleset

E — Pycodestyle Errors:
Enforces basic style guidelines such as spacing, indentation, and line formatting, helping maintain a consistent style.
F — Pyflakes Errors:
Helps catch code issues like unused variables, undefined names, and logical mistakes that could lead to runtime errors.
B — Bugbear Rules:
Highlights code patterns that are likely to cause bugs or unexpected behavior (e.g., mutable defaults, overly broad exceptions), improving reliability and safety.
I — Import Sorting (isort):
Ensures imports follow a consistent, predictable order, reducing merge conflicts and making dependencies easier to scan.
UP — pyupgrade Rules:
Automatically upgrades syntax to modern Python features (aligned with Python 3.10), simplifying code and reducing technical debt.

Ignored rule(s):

E741 — Ambiguous Variable Names:
Ignored to avoid false positives when short variable names (like l, I, O) are acceptable or intentional.

Scope

(Copies the changes in DeepLabCut/DeepLabCut-live#165, by @C-Achard)

• Bump pre-commit hooks to v6.0.0
• Move to Ruff (a fast and modern formatting tool) from black+isort only
  • Ruff is intended as a drop-in replacement
  • Ruff is faster than combining black+isort
• Add the following linting rules to pyproject.toml:

lint.select = ["E", "F", "B", "I", "UP"]
lint.ignore = ["E741"]
target-version = "py310"
fix = true
line-length = 120