contextlib.nullcontext: remove 2nd parameter from nullcontext[None] overload

Author: pinterior

stdlib/contextlib.pyi

@@ -210,7 +210,7 @@ if sys.version_info >= (3, 10):
     class nullcontext(AbstractContextManager[_T, None], AbstractAsyncContextManager[_T, None]):
         enter_result: _T
         @overload
-        def __init__(self: nullcontext[None], enter_result: None = None) -> None: ...
+        def __init__(self: nullcontext[None]) -> None: ...
         @overload
         def __init__(self: nullcontext[_T], enter_result: _T) -> None: ...  # pyright: ignore[reportInvalidTypeVarUse]  #11780
         def __enter__(self) -> _T: ...
@@ -222,7 +222,7 @@ else:
     class nullcontext(AbstractContextManager[_T, None]):
         enter_result: _T
         @overload
-        def __init__(self: nullcontext[None], enter_result: None = None) -> None: ...
+        def __init__(self: nullcontext[None]) -> None: ...
         @overload
         def __init__(self: nullcontext[_T], enter_result: _T) -> None: ...  # pyright: ignore[reportInvalidTypeVarUse]  #11780
         def __enter__(self) -> _T: ...