Remove obsolete OptExcInfo from sys (#13117)

stdlib/wsgiref/types.pyi

@@ -1,5 +1,5 @@
+from _typeshed import OptExcInfo
 from collections.abc import Callable, Iterable, Iterator
-from sys import _OptExcInfo
 from typing import Any, Protocol
 from typing_extensions import TypeAlias
 
@@ -7,7 +7,7 @@ __all__ = ["StartResponse", "WSGIEnvironment", "WSGIApplication", "InputStream",
 
 class StartResponse(Protocol):
     def __call__(
-        self, status: str, headers: list[tuple[str, str]], exc_info: _OptExcInfo | None = ..., /
+        self, status: str, headers: list[tuple[str, str]], exc_info: OptExcInfo | None = ..., /
     ) -> Callable[[bytes], object]: ...
 
 WSGIEnvironment: TypeAlias = dict[str, Any]