fix codestyle

Author: zenghsh3

python/paddle/fluid/tests/unittests/test_sampling_id_op.py

@@ -36,7 +36,7 @@ def test_check_output(self):
         y1 = self.out
         self.check_output_customized(self.verify_output)
         y2 = self.out
-        
+
         # check dtype
         assert y1.dtype == np.int64
         assert y2.dtype == np.int64