BLD: use nonvendor versioneer
This PR:
1. move versioneer config to pyproject.toml
2. use nonvendored version of versioneer

After this, we could enable PEP 517. 
@lithomas1  Does meson-Python require versioneer to be vendored?  > Does meson-Python require versioneer to be vendored?

Seems to work fine. Awesome, thanks @fangchenli. Always great to not vendor things if we don't have to 