Dolphin switch to KF6.
Merge branch 'kf6' into work/meven/dolphin-qt6-alpha
To be ready for KDE Gears 6 alpha
cc @felixernst
Following this we can update, sysadmin configuration and clean lefovers #ifdef
All MR tracking master will need to get rebased once merged, so to avoid unnecessary conflicts :
- let's stop accepting MR for master (unless they are KF5 specific) accept only for kf6,
- try to get merged MRs close to the finish line
Once there aren't many MR concerned by 2., then we can merge the MR.
Edited by Méven Car