adjust test to use commands

Author: siler

crates/bevy_transform/src/hierarchy/hierarchy_maintenance_system.rs

@@ -87,8 +87,10 @@ mod test {
         );
 
         // Parent `e1` to `e2`.
-        (*world.get_mut::<Parent>(children[0]).unwrap()).0 = children[1];
+        let mut commands = Commands::default();
+        commands.push_children(children[1], &[children[0]]);
 
+        commands.apply(&mut world, &mut resources);
         schedule.run(&mut world, &mut resources);
 
         assert_eq!(