Fix pre-commit formatting

Author: anubhav-0012

pandas/core/reshape/merge.py

@@ -1962,7 +1962,7 @@ def _validate_validate_kwd(self, validate: str) -> None:
             right_keys = self.orig_right.index
         else:
             right_keys = MultiIndex.from_arrays(self.right_join_keys)
-        
+
         left_unique = left_keys.is_unique
         right_unique = right_keys.is_unique
 
@@ -1978,7 +1978,7 @@ def sample_duplicates(keys, limit=10):
             if not left_unique and not right_unique:
                 left_sample = sample_duplicates(left_keys, limit=5)
                 right_sample = sample_duplicates(right_keys, limit=5)
-                
+
                 raise MergeError(
                     "Merge keys are not unique in either left "
                     "or right dataset; not a one-to-one merge. "
@@ -1988,23 +1988,25 @@ def sample_duplicates(keys, limit=10):
             if not left_unique:
                 sample = sample_duplicates(left_keys)
                 raise MergeError(
-                    "Merge keys are not unique in left dataset; not a one-to-one merge. "
+                    "Merge keys are not unique in left dataset; "
+                    "not a one-to-one merge. "
                     f"Offending keys (sample): {sample}"
                 )
             if not right_unique:
                 sample = sample_duplicates(right_keys)
                 raise MergeError(
-                    "Merge keys are not unique in right dataset; not a one-to-one merge. "
+                    "Merge keys are not unique in right dataset; "
+                    "not a one-to-one merge. "
                     f"Offending keys (sample): {sample}"
                 )
 
         elif validate in ["one_to_many", "1:m"]:
             if not left_unique:
                 sample = sample_duplicates(left_keys)
                 raise MergeError(
-                    "Merge keys are not unique in left dataset; not a one-to-many merge. "
+                    "Merge keys are not unique in left dataset; "
+                    "not a one-to-many merge. "
                     f"Offending keys (sample): {sample}"
-
                 )
 
         elif validate in ["many_to_one", "m:1"]:

pandas/tests/reshape/merge/test_merge.py

@@ -3122,6 +3122,7 @@ def test_merge_pyarrow_datetime_duplicates():
     expected = expected.convert_dtypes(dtype_backend="pyarrow")
     tm.assert_frame_equal(result, expected)
 
+
 def test_merge_validate_one_to_one_offending_keys():
     df = pd.DataFrame({"a": [1, 1, 3], "b": [4, 5, 6]})
     with pytest.raises(pd.errors.MergeError, match="Offending keys"):