Fixed an encoding problem in simplify suggestion

src/slic3r/GUI/Gizmos/GLGizmoSimplify.cpp

@@ -109,7 +109,7 @@ void GLGizmoSimplify::add_simplify_suggestion_notification(
     if (big_ids.empty()) return;
 
     for (size_t object_id : big_ids) {
-        std::string t = GUI::format(_u8L(
+        std::string t = GUI::format(_L(
             "Processing model '%1%' with more than 1M triangles "
             "could be slow. It is highly recommend to reduce "
             "amount of triangles."), objects[object_id]->name);