Upgrade tf version to fix security warning

examples/trials/ga_squad/requirements.txt

@@ -1 +1 @@
-tensorflow==1.13.1
+tensorflow==1.15.2

examples/trials/network_morphism/FashionMNIST/FashionMNIST_keras.py

@@ -152,7 +152,7 @@ def on_epoch_end(self, epoch, logs=None):
         if logs is None:
             logs = dict()
         logger.debug(logs)
-        nni.report_intermediate_result(logs["val_acc"])
+        nni.report_intermediate_result(logs["val_accuracy"])
 
 
 # Training

examples/trials/network_morphism/cifar10/cifar10_keras.py

@@ -152,7 +152,9 @@ def on_epoch_end(self, epoch, logs=None):
         if logs is None:
             logs = dict()
         logger.debug(logs)
-        nni.report_intermediate_result(logs["val_acc"])
+        # accuracy key for keras 2.2.2: val_acc
+        # for keras 2.3.1: val_accuracy
+        nni.report_intermediate_result(logs["val_accuracy"])
 
 
 # Training

examples/trials/network_morphism/requirements.txt

@@ -1,5 +1,5 @@
 numpy==1.14.2
-tensorflow==1.13.1
+tensorflow==1.15.2
 torchvision==0.2.1
-Keras==2.2.2
+Keras==2.3.1
 torch==0.4.1