title: TypeError: type object got multiple values for keyword argument 'training'
body: <p>I am checking an object detection collaboratory notebook and it's supposed to work properly.
  when i run its code to train the model it gives me it's error:</p>
  <pre><code>!keras_retinanet/bin/train.py \
  </code></pre>
  <p>--freeze-backbone <br />
  --random-transform <br />
  --weights {PRETRAINED_MODEL} <br />
  --batch-size 8 <br />
  --steps 500 <br />
  --epochs 10 <br />
  csv annotations.csv classes.csv
  TypeError: type object got multiple values for keyword argument 'training'</p>
  <p>the model does not train and i couldn't figure out the exact problem</p>