py-typing-extensions: updated to 4.8.0

Release 4.8.0 (September 17, 2023)

No changes since 4.8.0rc1.

Release 4.8.0rc1 (September 7, 2023)

- Add `typing_extensions.Doc`, as proposed by PEP 727. Patch by
  Sebasti叩n Ram鱈rez.
- Drop support for Python 3.7 (including PyPy-3.7). Patch by Alex Waygood.
- Fix bug where `get_original_bases()` would return incorrect results when
  called on a concrete subclass of a generic class. Patch by Alex Waygood
  (backporting https://github.com/python/cpython/pull/107584, by James
  Hilton-Balfe).
- Fix bug where `ParamSpec(default=...)` would raise a `TypeError` on Python
  versions <3.11. Patch by James Hilton-Balfe

(adam)