Fix adamw pytorch test

    tfopt = opt._create_tf_optimizer(global_step)

    assert isinstance(tfopt, tfa.optimizers.AdamW)

  @unittest.skipIf(not has_tensorflow_addons, 'TensorFlow Addons is not installed')

  @unittest.skipIf(not has_pytorch, 'PyTorch is not installed')

  def test_adamw_pytorch(self):

    """Test creating an AdamW optimizer."""

    opt = optimizers.AdamW(learning_rate=0.01)