* New features
  1. build(python): update install requires. 110bcbd7d16
  2. perf(train): use torch.cuda.apex and only use cuda:0 to do validate(). 10a87ddbf0390e907
* Bug fixes
  1. fix(sampler): use DistributedSampler only in train mode. bee2f3c06d2f1
* Breaking changes