Big diff: use lower-case list and dict (#5888)

stubs/mypy-extensions/mypy_extensions.pyi

@@ -1,6 +1,6 @@
 import abc
 import sys
-from typing import Any, Callable, Dict, Generic, ItemsView, KeysView, Mapping, Type, TypeVar, Union, ValuesView
+from typing import Any, Callable, Generic, ItemsView, KeysView, Mapping, Type, TypeVar, Union, ValuesView
 
 _T = TypeVar("_T")
 _U = TypeVar("_U")
@@ -25,7 +25,7 @@ class _TypedDict(Mapping[str, object], metaclass=abc.ABCMeta):
         def viewvalues(self) -> ValuesView[object]: ...
     def __delitem__(self, k: NoReturn) -> None: ...
 
-def TypedDict(typename: str, fields: Dict[str, Type[Any]], total: bool = ...) -> Type[Dict[str, Any]]: ...
+def TypedDict(typename: str, fields: dict[str, Type[Any]], total: bool = ...) -> Type[dict[str, Any]]: ...
 def Arg(type: _T = ..., name: str | None = ...) -> _T: ...
 def DefaultArg(type: _T = ..., name: str | None = ...) -> _T: ...
 def NamedArg(type: _T = ..., name: str | None = ...) -> _T: ...