Log Message:
py-validate-pyproject: updated to 0.9

Version 0.9
- Use ``tomllib`` from the standard library in Python 3.11+

Version 0.8.1
- Workaround typecheck inconsistencies between different Python versions
- Publish :pep:`561` type hints

Version 0.8
- New :pypi:`pre-commit` hook
- Allow multiple TOML files to be validated at once via **CLI**
  (*no changes regarding the Python API*).