torch version for using 'all_gather_object'

[Sunghwan Mun]

It seems that all_gather_object from torch.distributed is available since torch 1.7.0 version. (Not available with the minimum versions (1.6.x) of requirements.py)
Thanks for checking it out.

[lbjcom]

Thanks for the comment. Would you please make a PR for the requirements.txt?

[Sunghwan Mun]

@lbjcom @hsss Thank you so much for your reply :-)
I made a PR.
(This dependency issue seems to cause an error when evaluation during ddp training in torch 1.6.0 version.)