Fix: Use Qt::endl instead of deprecated endl
Hi.
This is my first patch ever to a KDE project. I hope I did not miss anything. I am also not a C++ dev... this patch is pretty easy, so I guess there's not much I could have messed up... at least it builds (against Qt5.15 on my nixos machine).
I hope I have not messed up anything else.
If this works out good, I will tackle a more sophisticated change