fix: the latest gunicorn remove six

now can be used in py2 and py3

Api/ProxyApi.py

@@ -87,7 +87,7 @@ def getStatus():
 
 if platform.system() != "Windows":
     import gunicorn.app.base
-    from gunicorn.six import iteritems
+    from six import iteritems
 
 
     class StandaloneApplication(gunicorn.app.base.BaseApplication):