[demo][bug] Setting estimator.updater must be executed before calling estimator.fit

[andafterall]

[codingfun2022]

Using estimator = ms.PyTorchEstimator(..., updater=ms.AdamTensorUpdater(adam_learning_rate), ...) is better.

[andafterall]

@intelligencegear
typo:
trian_dataset => train_dataset