Due to recent changes in argparse error message construction the test
that is checking for the non-existing split algorithm was failing.
python/cpython#117766

Fixed with a lenient error string check with additional dynamic algorithm
check.

Fix test failure in Python 3.14a

New version was released - https://github.com/pytest-dev/pytest/releases/tag/9.0.0

Allow to use pytest 9

- Add pytest 9.x to supported versions in changelog
- Migrate poetry.dev-dependencies to poetry.group.dev.dependencies
- Regenerate lock file with Poetry 2.3.2

Co-Authored-By: Claude Opus 4.5 <[email protected]>

- Add Python 3.14 to pyproject.toml classifiers
- Add Python 3.14 to CI test matrix
- Update changelog

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Add support for Python 3.14

- Remove Python 3.8 and 3.9 from pyproject.toml classifiers
- Update minimum Python version to 3.10
- Remove Python 3.8 and 3.9 from CI test matrix
- Update README requirements
- Update ruff and black target versions
- Modernize type hints to use built-in generics (list, dict, tuple)
  instead of typing module imports
- Update changelog

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Remove support for Python 3.8 and 3.9 (end-of-life)