Switch back to using object level normals

src/main.c

@@ -33,7 +33,7 @@ int main(void) {
   }
 
   Model obj = load_obj_file(arena, RESOURCE("head.obj"), RESOURCE("head.pnm"),
-                            RESOURCE("head_nm_tangent.pnm"));
+                            RESOURCE("head_nm.pnm"));
   if (IS_INVALID_MODEL(obj)) {
     return TINY_EXIT_MODEL_LOAD_FAILED;
   }