Bump CircleCI docker version to 278 (#15795)
Summary:
Just changing the version number doesn't seem to work. I needed to also fix macos brew parallel conflict
should this merge together with https://github.com/pytorch/ossci-job-dsl/pull/36 ?
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15795
Differential Revision: D13591839
Pulled By: yf225
fbshipit-source-id: 6b2a90943e63c8dcc4b6d9159eb54f1b5974c9ac
