style: fix ruff linting errors - remove whitespace from blank lines

Amp-Thread-ID: https://ampcode.com/threads/T-ab40799c-7282-451b-bdf6-4a74c73a62b7
Co-authored-by: Amp <[email protected]>

Author: vinitkumar

tests/test_parallel.py

@@ -303,7 +303,7 @@ def test_parallel_unsupported_type_error(self) -> None:
         """Test that unsupported types raise TypeError in parallel mode."""
         class CustomType:
             pass
-        
+
         data = {f"key{i}": CustomType() for i in range(15)}
         with pytest.raises(TypeError, match="Unsupported data type"):
             dicttoxml.dicttoxml(data, parallel=True, workers=4)
@@ -318,7 +318,7 @@ def test_parallel_with_bool_values(self) -> None:
     def test_parallel_with_datetime_values(self) -> None:
         """Test parallel processing with datetime values."""
         from datetime import datetime
-        
+
         data = {f"key{i}": datetime(2024, 1, i + 1) for i in range(15)}
         result_parallel = dicttoxml.dicttoxml(data, parallel=True, workers=4)
         result_serial = dicttoxml.dicttoxml(data, parallel=False)