keras.layers.normalization deprecated

[sqing73]

from keras.layers.normalization import BatchNormalization
could be changed to
from tensorflow.keras.layers import BatchNormalization

[jonkrohn]

Yep, you're right! For the sake of consistency with the book, I'm going to leave it as-is in this particular repo, but you can see the updated (TensorFlow 2.x) code that uses the tensorflow.keras. nomenclature in the newer, analogous repo here.