[skip ci] Add GitHub Actions label for g3.16xlarge (#60888)
Summary:
Prerequisite for https://github.com/pytorch/pytorch/issues/60221.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60888
Reviewed By: seemethere
Differential Revision: D29436592
Pulled By: samestep
fbshipit-source-id: b3254139ec9c46c533f8f951a9ede3b372a65536
