Update logging to warning since warn is deprecated (#828)

Author: seanpmorgan

tensorflow_addons/layers/wrappers.py

@@ -64,7 +64,7 @@ def __init__(self, layer, data_init=True, **kwargs):
         self.is_rnn = isinstance(self.layer, tf.keras.layers.RNN)
 
         if self.data_init and self.is_rnn:
-            logging.warn(
+            logging.warning(
                 "WeightNormalization: Using `data_init=True` with RNNs "
                 "is advised against by the paper. Use `data_init=False`.")