Create a new branch on transformers origin (not a fork!).
The branch name has to start with either ci_ or ci- (main triggers it too, but we can't do PRs on
   main). It also gets triggered only for specific paths - you can find the up-to-date definition in case it
   changed since this document has been written here under push:
Create a PR from this branch.
Then you can see the job appear here. It may not run right away if there
   is a backlog.