fix merge conflict resolution error

bitsandbytes/autograd/_functions.py

@@ -1,8 +1,8 @@
-from dataclasses import dataclass
-from functools import reduce  # Required in Python 3
 import operator
-from typing import Optional, Tuple
 import warnings
+from dataclasses import dataclass
+from functools import reduce  # Required in Python 3
+from typing import Tuple, Optional, Callable
 from warnings import warn
 
 import torch