[neon-notifications] kmarkdownwebview new version 0.5.4

[Neon CI]

https://build.neon.kde.org/job/watcher_release_neon-packaging_kmarkdownwebview/302/display/redirect

#<Debian::UScan::DEHS::Package:0x000055c2059e7920 @name="kmarkdownwebview", @debian_uversion="0.5.3", @debian_mangled_uversion="0.5.3", @upstream_version="0.5.4", @upstream_url="http://download.kde.internal.neon.kde.org/stable/kmarkdownwebview/0.5.4/src/kmarkdownwebview-0.5.4.tar.xz", @status="Newer version available">