Fix utils/model pyre fixme issues (#1606)

Summary:
Pull Request resolved: #1606

Fixing unresolved pyre fixme issues in corresponding file

Reviewed By: sarahtranfb

Differential Revision: D76737258

fbshipit-source-id: 7e6dd861f2707f77e8321360842affd4cbb5e206

Author: Vivek Miglani

captum/_utils/models/model.py

@@ -22,8 +22,7 @@ class Model(ABC):
     def fit(
         self,
         train_data: DataLoader,
-        # pyre-fixme[2]: Parameter must be annotated.
-        **kwargs,
+        **kwargs: object,
     ) -> Optional[Dict[str, Union[int, float, Tensor]]]:
         r"""
         Override this method to actually train your model.