Fix minor ugv_cmd issue

tools/ugv_cmd.py

@@ -9,7 +9,7 @@ import yaml
 try:
     from yaml import CLoader as YamlLoader, CDumper as YamlDumper
 except ImportError:
-    from yaml import YamlLoader, YamlDumper
+    from yaml import Loader as YamlLoader, Dumper as YamlDumper
 import types
 
 from ugv import UGVComms