Use typing_extensions.TypedDict on Python < 3.12

The current use of typing.TypedDict` in `pydantic_core.__init__.py`
on Python 3.9 to 3.11 is inconsistent Pydantic.
For further information visit https://errors.pydantic.dev/2.8/u/typed-dict-version

Author: candleindark

python/pydantic_core/__init__.py

@@ -34,7 +34,7 @@
 else:
     from typing import NotRequired as _NotRequired
 
-if _sys.version_info < (3, 9):
+if _sys.version_info < (3, 12):
     from typing_extensions import TypedDict as _TypedDict
 else:
     from typing import TypedDict as _TypedDict