Create PEP561 compatible typed package

[tkoft]

https://mypy.readthedocs.io/en/latest/installed_packages.html#creating-pep-561-compatible-packages

Looks like this library is typed, but sadly the package distributed to PyPI doesn't include the stubs. They have to be explicitly included in setup.py as package_data.

However, it looks like with setuptools v69, this will happen by default. So upgrading setuptools would fix this too.
pypa/setuptools#3136