[neon-notifications] Dev Required: qcustomplot - 2.1.1

[Neon CI]

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

#<Debian::UScan::DEHS::Package:0x0000559df0fc7f90 @name="qcustomplot", @debian_uversion="2.1.0+dfsg1", @debian_mangled_uversion="2.1.0", @upstream_version="2.1.1", @upstream_url="http://www.qcustomplot.com/release/2.1.1/QCustomPlot.tar.gz", @status="Newer version available">