CircleCI deprecated image migration

[vfdev-5]

Message from Circle CI:

Hello,
We are deprecating Ubuntu 16.04-based machine images on CircleCI in preparation for an EOL on Tuesday, May 31, 2022 to ensure your builds remain secure. For a detailed overview of how this will affect your workflow, read the blog article here.
We will also be conducting temporary brownouts on Tuesday, March 29, 2022, and again on Tuesday, April 26, 2022 during which these images will be unavailable.
We are contacting you because one or more of your projects has a job that uses an Ubuntu 16.04-based image.
The project(s) using an image based on Ubuntu 16.04 are:
[functorch] [functorch] [functorch] [functorch][functorch] [functorch]...
If you have specified an Ubuntu 16.04-based image please see our migration guide to upgrade to a newer version of Ubuntu image in order to avoid any service disruption during the brownout & subsequent EOL.

• https://circleci.com/docs/2.0/images/linux-vm/16.04-to-20.04-migration/

[zou3519]

Actionable to figure out how PyTorch is dealing with this and copy them

[vfdev-5]

PyTorch is on GHA now, vision is still on CircleCI

[samdow]

Still seeing some PyTorch tests using CircleCI. Looks like they upgraded to 20.04. We can probably use that one unless we want to upgrade further

[vfdev-5]

That's true that there are some tests running on circleci. Yes, we can upgrade to 20.04.