Use typing_extensions.Self instead of _typeshed.Self (#9702)

stubs/mypy-extensions/mypy_extensions.pyi

@@ -1,10 +1,10 @@
 import abc
 import sys
 from _collections_abc import dict_items, dict_keys, dict_values
-from _typeshed import IdentityFunction, Self
+from _typeshed import IdentityFunction
 from collections.abc import Mapping
 from typing import Any, ClassVar, Generic, TypeVar, overload, type_check_only
-from typing_extensions import Never
+from typing_extensions import Never, Self
 
 _T = TypeVar("_T")
 _U = TypeVar("_U")
@@ -16,20 +16,20 @@ class _TypedDict(Mapping[str, object], metaclass=abc.ABCMeta):
     __total__: ClassVar[bool]
     # Unlike typing(_extensions).TypedDict,
     # subclasses of mypy_extensions.TypedDict do NOT have the __required_keys__ and __optional_keys__ ClassVars
-    def copy(self: Self) -> Self: ...
+    def copy(self) -> Self: ...
     # Using Never so that only calls using mypy plugin hook that specialize the signature
     # can go through.
     def setdefault(self, k: Never, default: object) -> object: ...
     # Mypy plugin hook for 'pop' expects that 'default' has a type variable type.
     def pop(self, k: Never, default: _T = ...) -> object: ...  # pyright: ignore[reportInvalidTypeVarUse]
-    def update(self: Self, __m: Self) -> None: ...
+    def update(self, __m: Self) -> None: ...
     def items(self) -> dict_items[str, object]: ...
     def keys(self) -> dict_keys[str, object]: ...
     def values(self) -> dict_values[str, object]: ...
     def __delitem__(self, k: Never) -> None: ...
     if sys.version_info >= (3, 9):
-        def __or__(self: Self, __other: Self) -> Self: ...
-        def __ior__(self: Self, __other: Self) -> Self: ...
+        def __or__(self, __other: Self) -> Self: ...
+        def __ior__(self, __other: Self) -> Self: ...
 
 def TypedDict(typename: str, fields: dict[str, type[Any]], total: bool = ...) -> type[dict[str, Any]]: ...
 @overload