Fix ruff errors

Author: kosiew

python/datafusion/dataframe.py

@@ -1135,7 +1135,7 @@ def __arrow_c_stream__(self, requested_schema: object | None = None) -> object:
             >>> stream = df.__arrow_c_stream__(schema)
             >>> capsule = schema._export_to_c_capsule()
             >>> stream = df.__arrow_c_stream__(capsule)
-        
+
         Notes:
             The Arrow C Data Interface PyCapsule details are documented by Apache
             Arrow and can be found at:

python/tests/test_io.py

@@ -114,8 +114,8 @@ def test_arrow_c_stream_large_dataset(ctx):
     reader = pa.RecordBatchReader.from_stream(df)
 
     # Track RSS before consuming batches
-    # RSS is a practical measure of RAM usage visible to the OS. It excludes memory 
-    # that has been swapped out and provides a simple cross-platform-ish indicator 
+    # RSS is a practical measure of RAM usage visible to the OS. It excludes memory
+    # that has been swapped out and provides a simple cross-platform-ish indicator
     # (psutil normalizes per-OS sources).
     psutil = pytest.importorskip("psutil")
     process = psutil.Process()