Add missing contextlib.contextmanager to sklearn.config_context (#393)

* add missing `contextlib.contextmanager` to `sklearn.config_context`

* Update stubs/sklearn/_config.pyi

Co-authored-by: Avasam <samuel.06@hotmail.com>

---------

Co-authored-by: Avasam <samuel.06@hotmail.com>

Author: fhoehle

stubs/sklearn/_config.pyi

@@ -1,4 +1,5 @@
-from collections.abc import Iterator
+from collections.abc import Generator
+from contextlib import contextmanager
 from typing import Literal
 
 from ._typing import Int
@@ -19,6 +20,7 @@ def set_config(
     enable_metadata_routing: None | bool = None,
     skip_parameter_validation: None | bool = None,
 ) -> None: ...
+@contextmanager
 def config_context(
     *,
     assume_finite: None | bool = None,
@@ -31,4 +33,4 @@ def config_context(
     transform_output: None | str = None,
     enable_metadata_routing: None | bool = None,
     skip_parameter_validation: None | bool = None,
-) -> Iterator[None]: ...
+) -> Generator[None, None, None]: ...