Update constant_fold.py

Author: BobTheBuidler

mypyc/irbuild/constant_fold.py

@@ -10,7 +10,7 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Final, Union
+from typing import TYPE_CHECKING, Callable, Final, Union
 
 from mypy.constant_fold import constant_fold_binary_op, constant_fold_unary_op
 from mypy.nodes import (