Update test_preserve_leading_zeros.py

Author: dxdc

pandas/tests/io/parser/test_preserve_leading_zeros.py

@@ -2,9 +2,10 @@
 
 import pytest
 
-import pandas._testing as tm
 from pandas.errors import ParserWarning
 
+import pandas._testing as tm
+
 
 def test_leading_zeros_preserved_with_dtype_str(all_parsers, request):
     # GH#57666: pyarrow engine strips leading zeros when dtype=str is passed