Update neus.py

[MobiusLqm]

#this make sure it will be saved after training, if not, when execute test scripts by setting '--test', this hyperparameter will be set to zero, Which will cause significant drops in performance. When testing ,on_predict_batch_start will set cos_anneal_ratio to zero, because self.current_epoch equals to zero at the beginning.

[MobiusLqm]

This pull request is to deal with the bugs mentioned in #120 .

[weihan1]

Thanks for this change, it's very helpful!