Fix minor typo

Author: LeonShams

tensorflow_addons/layers/noisy_dense.py

@@ -22,7 +22,7 @@
 from tensorflow.python.framework import dtypes, tensor_shape, sparse_tensor
 from tensorflow.python.keras.engine.base_layer import Layer
 
-@tf..utils.register_keras_serializable(package="Addons")
+@tf.utils.register_keras_serializable(package="Addons")
 class NoisyDense(Layer):
   """Like normal dense layer but random noisy is added to the weights matrix. But
   as the network improves the random noise is decayed until it is insignificant.