[neon-notifications] Dev Required: mlt - 7.4.0

[Neon CI]

https://build.neon.kde.org/job/watcher_release_backports-focal_mlt/105/display/redirect

#<Debian::UScan::DEHS::Package:0x000055a2e0ba5148 @name="mlt", @debian_uversion="7.2.0", @debian_mangled_uversion="7.2.0", @upstream_version="7.4.0", @upstream_url="https://github.com/mltframework/mlt/archive/refs/tags/v7.4.0.tar.gz", @status="Newer version available">