fix rhai insert test

Author: aggyomfg

assets/tests/insert/vec.rhai

@@ -1,6 +1,6 @@
 let res_type = world.get_type_by_name.call("TestResourceWithVariousFields");
 let res = world.get_resource.call(res_type);
 
-res.vec_usize.insert.call(2, 42);
+res.vec_usize[2] = 42;
 
 assert(res.vec_usize[2] == 42, "insert did not work");