Fix typo (#651)

keras_nlp/models/bert/bert_backbone.py

@@ -139,7 +139,7 @@ def __init__(
             name="segment_embedding",
         )(segment_id_input)
 
-        # Sum, normailze and apply dropout to embeddings.
+        # Sum, normalize and apply dropout to embeddings.
         x = keras.layers.Add()(
             (token_embedding, position_embedding, segment_embedding)
         )