Fix lint. (#7383)

W293 blank line contains whitespace.

Author: tseaver

bigquery/google/cloud/bigquery/table.py

@@ -1382,7 +1382,7 @@ def get_dataframe(stream):
 
     def to_dataframe(self, bqstorage_client=None, dtypes=None):
         """Create a pandas DataFrame by loading all pages of a query.
-           
+
 
         Args:
             bqstorage_client ( \