typing_extensions should be a dependency

[kiyoon]

Fresh-installing pynvim on a new environment will fail to import the module due to the lack of typing_extensions (at least in Python 3.9). Thus the package should be listed as a dependency, maybe depending on the python version.

[kiyoon]

I think it's already addressed in the master branch, but maybe not the pypi version 0.5.1. Sorry! Closing as completed

[wookayin]

While I can see that this has been fixed in #581, I don't see why CI hadn't been unable to catch this (before #581 was merged).

EDIT: I got it, the following is still executed during pip install -e., but this dependency is not published to PyPI as the release was made with python >= 3.12. We should make a new release anyway; thanks for reporting.

if sys.version_info < (3, 12):
    install_requires.append('typing-extensions>=4.5')

[kiyoon]

@wookayin ahh that makes sense. Very interesting bug! Thanks for investigating :))