Update stdlib/importlib/util.pyi

Co-authored-by: Sebastian Rittau <[email protected]>

Author: guoci

stdlib/importlib/util.pyi

@@ -49,6 +49,8 @@ def source_hash(source_bytes: ReadableBuffer) -> bytes: ...
 if sys.version_info >= (3, 12):
     class _incompatible_extension_module_restrictions:
         def __init__(self, *, disable_check: bool) -> None: ...
+            disable_check: bool
+            old: Literal[-1, 0, -1]  # exists only while entered
         def __enter__(self) -> Self: ...
         def __exit__(
             self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None