make it compatible for pytorch latest version

[jizongFox]

Hi, just noticed this wonderful work. I have made this code available for latest PyTorch version by providing minor revisions. Please consider merging.

[izmailovpavel]

Hi @jizongFox thanks for the PR. I will be able to take a close look in a week or so. I don't know if we want to add tqdm in adjust_learning_rate. If we do, why not in the train epoch as well? Also, I guess we would want to somehow preserve compatibility with older PyTorch versions? @timgaripov what do you think?