[neon-notifications] Dev Required: appstream - 0.14.6

[Neon CI]

https://build.neon.kde.org/job/watcher_release_backports-focal_appstream/4/display/redirect

#<Debian::UScan::DEHS::Package:0x000055e9f5ee8f38 @name="appstream", @debian_uversion="0.14.4", @debian_mangled_uversion="0.14.4", @upstream_version="0.14.6", @upstream_url="https://www.freedesktop.org/software/appstream/releases/AppStream-0.14.6.tar.xz", @status="Newer version available">