[neon-notifications] libquotient new version 0.6.4

[Neon CI]

https://build.neon.kde.org/job/watcher_release_neon-packaging_libquotient/65/display/redirect

#<Debian::UScan::DEHS::Package:0x00007f81c000bf38 @name="libquotient", @debian_uversion="0.6.2", @debian_mangled_uversion="0.6.2", @upstream_version="0.6.4", @upstream_url="https://github.com/quotient-im/libQuotient/archive/0.6.4.tar.gz", @status="Newer version available">