$NetBSD$

Use GTK3, since that's how we build wxWidgets.

--- CMakeLists.txt.orig	2022-04-22 11:01:19.000000000 +0000
+++ CMakeLists.txt
@@ -38,7 +38,7 @@ CMAKE_DEPENDENT_OPTION(SLIC3R_DESKTOP_IN
 
 set(OPENVDB_FIND_MODULE_PATH "" CACHE PATH "Path to OpenVDB installation's find modules.")
 
-set(SLIC3R_GTK "2" CACHE STRING "GTK version to use with wxWidgets on Linux")
+set(SLIC3R_GTK "3" CACHE STRING "GTK version to use with wxWidgets on Linux")
 
 set(IS_CROSS_COMPILE FALSE)
 
