this package seems to have new commits in its VCS but has
not yet updated debian/changelog. You should consider updating
the Debian changelog and uploading this new version into the archive.
Here are the relevant commit logs:
Author: Unit 193 <email@example.com>
Date: Tue Jan 5 18:49:03 2021 -0500
d/copyright: Correct upstream name, lightdm → lightdm-gtk-greeter.