convolutional_network_raw.ipynb doens't work for python3

[seilgu]

https://github.com/aymericdamien/TensorFlow-Examples/blob/master/tensorflow_v2/notebooks/3_NeuralNetworks/convolutional_network_raw.ipynb

trainable_variables = weights.values() + biases.values() doesn't work.
Also if I write trainable_variables = list(weights.values()) + list(biases.values()), I have to turn on tf.enable_eager_execution(), but the training result is wrong, accuracy is around 0.1 and not improving.

[yui-py]

Convert dict_values to list. It works well
trainable_variables = list(weights.values()) + list(biases.values())