Update CircleCI config to use Docker images from "pytorch" account (#29835)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29835
Using images from personal accounts restricts our ability to push
updates in a timely manner.
Test Plan: CI
Reviewed By: soumith
Differential Revision: D18524393
Pulled By: dreiss
fbshipit-source-id: f12dd3ce50c8362e152ed265e2d24bcb073dcfd4
