Fix/update linting checking and formatting

[yuriverweij]

This pull request modernizes the codebase by updating the minimum supported Python version to 3.10, switching code formatting and linting from Black and flake8 to Ruff, and updating relevant documentation and configuration files. It also updates type annotations to use Python 3.10+ syntax and cleans up imports for better readability and maintainability.

Python version and compatibility updates:

• Updated the minimum required Python version from 3.8 to 3.10 in documentation (README.rst, docs/index.html), packaging (setup.py), and CI configuration (.github/workflows/CI.yml). Removed references to unsupported versions and updated PyPy version to pypy-3.10.

Linting and formatting tool migration:

• Replaced Black and flake8 with Ruff for code formatting and linting. Updated configuration files (pyproject.toml, .flake8 removed), development requirements (requirements-dev.txt), and documentation (CONTRIBUTING.rst) to reflect this change.

Type annotation modernization:

• Updated type annotations throughout the codebase to use Python 3.10+ syntax (e.g., str | None instead of Optional[str], list[...] instead of List[...]).

General code cleanup and import improvements:

• Cleaned up and reordered imports for clarity and consistency, and replaced deprecated or legacy constructs (e.g., using NamedTuple instead of namedtuple).