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

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src/black/concurrency.py

@@ -9,10 +9,10 @@
 import os
 import signal
 import sys
+import traceback
 from concurrent.futures import Executor, ProcessPoolExecutor, ThreadPoolExecutor
 from multiprocessing import Manager
 from pathlib import Path
-import traceback
 from typing import Any, Iterable, Optional, Set
 
 from mypy_extensions import mypyc_attr