[3.11] typing: Add more tests for TypeVar (GH-104571) by JelleZijlstra · Pull Request #104577 · python/cpython

During the PEP 695 implementation at one point I made
TypeVar.__name__ return garbage, and all of test_typing passed.
So I decided to add a few more tests. In the process I discovered
a minor incompatibility from the C implementation of TypeVar:
empty constraints were returned as None instead of an empty tuple..
(cherry picked from commit 2693194)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>