fix: convert ARROW_STREAM_NAME to CString for PyCapsule creation

Author: kosiew

src/dataframe.rs

@@ -971,7 +971,9 @@ impl PyDataFrame {
         // PyArrow imports the capsule it assumes ownership of the stream and
         // nulls out the capsule's internal pointer so the destructor does not
         // free it twice.
-        PyCapsule::new(py, stream, Some(ARROW_STREAM_NAME)).map_err(Into::into)
+        // ARROW_STREAM_NAME is a `&CStr`; PyCapsule::new expects an
+        // `Option<CString>` for the name, so convert it here.
+        PyCapsule::new(py, stream, Some(ARROW_STREAM_NAME.into())).map_err(Into::into)
     }
 
     fn execute_stream(&self, py: Python) -> PyDataFusionResult<PyRecordBatchStream> {