fix linting error

Author: charlesdong1991

Diff for: pandas/tests/test_strings.py

@@ -3214,7 +3214,8 @@ def test_replace_warning_single_character(self, input_array,
         if warn:
             with tm.assert_produces_warning(FutureWarning,
                                             check_stacklevel=False):
-                result = values.str.replace(single_char, replace_char, regex=None)
+                result = values.str.replace(single_char, replace_char,
+                                            regex=None)
         else:
             result = values.str.replace(single_char, replace_char)