Convert update_meshes.py script to py3

stretch_description/meshes/update_meshes.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import os
 import stretch_body.hello_utils as hu
 batch_name = hu.read_fleet_yaml('stretch_re1_factory_params.yaml')['robot']['batch_name'].lower()