[3.12] gh-116782: Mention `__type_params__` in `inspect.getmembers` docs (GH-116783) (#116870)

gh-116782: Mention `__type_params__` in `inspect.getmembers` docs (GH-116783)
(cherry picked from commit 16349868d396cc1bff5188de3638321e87fe0293)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>