[GTK3] Fix treeview hover colour
Summary:
Treeviews now reflect the Qt theme more accurately when hovering items.
BUG: 414263
FIXED-IN: 5.18
Test Plan:
Before:
After:
Reviewers: Breeze, VDG, ngraham
Reviewed By: Breeze, VDG, ngraham
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D26591