Updated tutorial to work with tobj 3.0.x

docs/beginner/tutorial9-models/README.md

@@ -200,7 +200,14 @@ impl Model {
         layout: &wgpu::BindGroupLayout,
         path: P,
     ) -> Result<Self> {
-        let (obj_models, obj_materials) = tobj::load_obj(path.as_ref(), true)?;
+        let (obj_models, obj_materials) = tobj::load_obj(path.as_ref(), &LoadOptions {
+                triangulate: true,
+                single_index: true,
+                ..Default::default()
+            },
+        )?;
+
+        let obj_materials = obj_materials?;
 
         // We're assuming that the texture files are stored with the obj file
         let containing_folder = path.as_ref().parent()