Fix missing export for reversible embedding (#1327)

Author: mattdangerw

keras_nlp/layers/__init__.py

@@ -19,6 +19,7 @@
 from keras_nlp.layers.modeling.lora_dense import LoraDense
 from keras_nlp.layers.modeling.masked_lm_head import MaskedLMHead
 from keras_nlp.layers.modeling.position_embedding import PositionEmbedding
+from keras_nlp.layers.modeling.reversible_embedding import ReversibleEmbedding
 from keras_nlp.layers.modeling.rotary_embedding import RotaryEmbedding
 from keras_nlp.layers.modeling.sine_position_encoding import (
     SinePositionEncoding,