fix: `poetry run pytest` raises `SyntaxError: invalid escape sequence \S`

[waketzheng]

Fixes #465

Checklist

• [x] poetry run pytest
• [x] pre-commit run --all-files
• [x] tox

Motivation and Context

As the docopt project has been not maintained for many years, shall we to use another one to replace it: https://github.com/docopt/docopt/pull/507#issuecomment-2027452758 https://github.com/jazzband/docopt-ng