[pre-commit.ci] auto fixes from pre-commit.com hooks

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Author: pre-commit-ci[bot]

mypyc/irbuild/constant_fold.py

@@ -10,7 +10,8 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Callable, Final, TypeVar, Union
+from collections.abc import Callable
+from typing import TYPE_CHECKING, Final, TypeVar
 
 from mypy.constant_fold import constant_fold_binary_op, constant_fold_unary_op
 from mypy.nodes import (