Lingering dependencies on Qt 5 and Kf 5

[Shmerl <shtetldik+shmerl@gmail.com>]

While a lot of KDE packages already fully switched to Qt 6 and Kf 6, some still

have some lingering dependencies while they could avoid it.

For example kup-backup allows it upstream:

https://invent.kde.org/system/kup/-/blob/master/CMakeLists.txt?ref_type=heads#L51

Same for a few lingering dependencies in kdenlive.

I opened bugs for that, hopefully maintainers will have a chance to look at it

before the freeze.

Regards,

Shmerl.