title: Keras 'set_session' not available for Tensorflow 2.0
body: <p>Attempting to do the following:</p>
  <pre><code>import tensorflow as tf
  from keras.models import load_model, Model
  from keras import backend as K
  
  sess = tf.compat.v1.Session()
  K.set_session(sess)
  </code></pre>
  <p>When I run this in Google Colab I get:</p>
  <pre><code>RuntimeError: `set_session` is not available when using TensorFlow 2.0.
  </code></pre>
  <p>Does anyone know how to fix this?</p>