Replace LayerRNNCell with AbstractRNNCell

Signed-off-by: Simon Zhao <[email protected]>

recommenders/models/deeprec/models/sequential/sum_cells.py

@@ -3,7 +3,10 @@
 
 import numpy as np
 import tensorflow as tf
-from keras.layers.legacy_rnn.rnn_cell_impl import LayerRNNCell
+try:
+    from keras.layers.legacy_rnn.rnn_cell_impl import LayerRNNCell
+except:
+    from keras.layers.rnn import AbstractRNNCell as LayerRNNCell
 from tensorflow.python.eager import context
 from tensorflow.python.keras import activations
 from tensorflow.python.keras import initializers

setup.py

@@ -72,7 +72,7 @@
         "pytest>=3.6.4",
         "pytest-cov>=2.12.1",
         "pytest-mock>=3.6.1",  # for access to mock fixtures in pytest
-        "packaging>=20.9",  # for version comparison in test_dependency_security.py
+        "packaging>=20.9",     # for version comparison in test_dependency_security.py
     ],
 }
 # For the brave of heart