The package has a debian/watch file, but the last attempt
to use it for checking for newer upstream versions failed with
an error:
In debian/watch no matching files for watch line https://gitlab.com/bgermann/unrar-free/tags?sort=updated_desc archive/(?:[-_]?[Vv]?(\d[\-+\.:\~\da-zA-Z]*))/unrar-free-\d\S*\.tar\.gz