fix Ruff errors

Author: kosiew

python/datafusion/dataframe.py

@@ -811,7 +811,7 @@ def _prepare_join(
             and isinstance(on[0], list)
             and isinstance(on[1], list)
         ):
-            # We know this is safe because we've checked the types            
+            # We know this is safe because we've checked the types
             join_keys = on  # type: ignore[assignment]
             resolved_on = None
         else:

python/tests/test_dataframe.py

@@ -1940,7 +1940,6 @@ def test_write_parquet_with_options_encoding(tmp_path, encoding, data_types, res
             data["float"] = [1.01, 2.02, 3.03]
         elif data_type == "str":
             data["str"] = ["a", "b", "c"]
-
         elif data_type == "bool":
             data["bool"] = [True, False, True]