fix pre-commit error from base checkpointer

Summary:
Fixes pre commit error reported here
 {F1380609628} 
as the import is no longer used

Reviewed By: schwarzmx

Differential Revision: D53136435

torchtnt/framework/callbacks/base_checkpointer.py

@@ -12,7 +12,6 @@
 from typing import Any, cast, Iterable, List, Literal, Optional, Union
 
 import torch.distributed as dist
-from pyre_extensions import none_throws
 
 from torchtnt.framework.callback import Callback
 from torchtnt.framework.callbacks._checkpoint_utils import (