message: Removing duplicate `six` requirement in setup.py.
diff: @@ -60,7 +60,6 @@ REQUIRED_PACKAGES = [
  'keras_preprocessing >= 1.0.5',
  'numpy >= 1.16.0, < 2.0',
  'opt_einsum >= 2.3.2',
  - 'six >= 1.10.0',
  'protobuf >= 3.6.1',
  'tensorboard >= 2.0.0, < 2.1.0',
  'tensorflow_estimator >= 2.0.0, < 2.1.0',
  