fix smart_cond issue

Author: carusyte

corl/model/tf2/common.py

@@ -4,7 +4,7 @@
 from time import strftime
 
 from tensorflow.python.keras.utils import tf_utils
-from tensorflow.python.framework import smart_cond
+from tensorflow.python.framework.smart_cond import smart_cond
 
 class AlphaDropout(keras.layers.Layer):
   """Applies Alpha Dropout to the input.

model/common.py

@@ -4,7 +4,7 @@
 from time import strftime
 
 from tensorflow.python.keras.utils import tf_utils
-from tensorflow.python.framework import smart_cond
+from tensorflow.python.framework.smart_cond import smart_cond
 
 class AlphaDropout(keras.layers.Layer):
   """Applies Alpha Dropout to the input.