message: Enable test_rnn_gru_simple in backend test
diff: @@ -319,7 +319,6 @@ node_tests = [
  dim_in=32,
  num_layers=3,
  skip_input_transform=True),
  - # disabled for now as Caffe2 backend doesn't support optional inputs
  - # _create_test(
  - # "test_rnn_gru_simple", cell_type='gru', hidden_size=32, dim_in=15),
  + _create_test(
  + "test_rnn_gru_simple", cell_type='gru', hidden_size=32, dim_in=15),
  ]
  