Fix whitespace on blank line 1918:1: W293

Author: ryankarlos

pandas/core/frame.py

@@ -1918,7 +1918,7 @@ def to_stata(self, fname, convert_dates=None, write_index=True,
             * Categorical label contains more than 32,000 characters
 
             .. versionadded:: 0.19.0
-            
+
         See Also
         --------
         pandas.read_stata : Import Stata data files.