[stdlib] Add __interactivehook__ to sys module (#15024)

Author: guoci

stdlib/sys/__init__.pyi

@@ -424,6 +424,8 @@ if sys.platform == "win32":
 
 def intern(string: str, /) -> str: ...
 
+__interactivehook__: Callable[[], object]
+
 if sys.version_info >= (3, 13):
     def _is_gil_enabled() -> bool: ...
     def _clear_internal_caches() -> None: ...