FIX: auto arrange crashes with a single triangle

convexHull of a triangle should be valid.

jira: STUDIO-8297
Change-Id: Icb4b2310c173f88f2b499c8407d79ff00850dc77

src/libnest2d/include/libnest2d/geometry_traits.hpp

@@ -1053,7 +1053,7 @@ inline S convexHull(const S& sh, const PathTag&)
     namespace sl = shapelike;
     
     size_t edges = sl::cend(sh) - sl::cbegin(sh);
-    if(edges <= 3) return {};
+    if(edges < 3) return {};
     
     bool closed = false;
     std::vector<Point> U, L;