Set ref for linux_job checkout in lint (#96317)
test-infra's linux_job uses github.ref as the default value for the ref, which is the branch, so it checks out the most recent commit on the branch.
Might be better to fix this on the test-infra side instead
Pull Request resolved: https://github.com/pytorch/pytorch/pull/96317
Approved by: https://github.com/huydhn
