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Running pre-commit on all files after replacing reorder-python-imports by isort.

doc/en/example/multipython.py

@@ -1,12 +1,12 @@
 """Module containing a parametrized tests testing cross-python serialization
 via the pickle module."""
+
 import shutil
 import subprocess
 import textwrap
 
 import pytest
 
-
 pythonlist = ["python3.9", "python3.10", "python3.11"]