use_release_issue() suggests using unmaintained package in checklist

[adamhsparks]

When creating a new issue with use_release_issue() the checklist includes revdepcheck::revdep_check(num_workers = 4)), but the README for {revdepcheck} suggests that this may not be a good idea, "❗ This package is not actively maintained".

[jennybc]

This disclaimer has since been removed from revdepcheck, so I think this can safely remain in the checklist.