Currently if a PR modifies any file that configures a Github action
(e.g. a workflow file), the caretaker might face an error when merging
such PR:
```
! [remote rejected] merge_pr_target_11.2.x -> 11.2.x (refusing to allow a Personal Access Token to create or update workflow
```
This happens because Github requires the token being used for the
push operation to have the `workflow` scope set. This is a special
scope added by Github to ensure that no changes can be made on
upstream branches that might expose the `GITHUB_TOKEN` environment
variable, which is available for push builds and could cause the
token being leaked.
With this commit we enforce that the caretaker adds the workflow
scope to their github token. Since PRs can only be merged if reviewed
thoroughly, it's acceptable to allow workflow file changes being
merged through the merge tool by the caretaker (especially since we
also allow CircleCI config files being merged with the default
`repo`/`public_repo` scope).
PR Close#41989
2843f15e8c