math/qalculate-qt: Update to 5.0.0
Drop local Qt 5.x support for ease of maintainership and its eventual
removal from the FreeBSD ports tree. Qt 5.x has been long deprecated
upstream [1] and the FreeBSD kde@ team recommends using Qt 6.x for
end-user applications whenever possible.
https://github.com/Qalculate/qalculate-qt/releases/tag/v5.0.0