Version 2.0.0 is out and compatible with KDE Frameworks 5. Here is the link to the tag: https://quickgit.kde.org/?p=skanlite.git&a=commit&h=cebc21c7ea1c1dcfe7390bf712f053d5880c4fd6
It's in the kde overlay. https://github.com/gentoo/kde/blob/master/kde-misc/skanlite/skanlite-2.0.ebuild We'll move it to the tree at a later point in time.