[neon-notifications] ksmtp new version 19.12.3

[Neon CI]

https://build.neon.kde.org/job/watcher_release_kde_ksmtp/672/display/redirect

#<Debian::UScan::DEHS::Package:0x000055fa57412bf0 @name="ksmtp", @debian_uversion="19.12.2", @debian_mangled_uversion="19.12.2", @upstream_version="19.12.3", @upstream_url="http://download.kde.internal.neon.kde.org/stable/release-service/19.12.3/src/ksmtp-19.12.3.tar.xz", @status="Newer version available">