fix: bug修复

src/core/callcenter/agent.py

@@ -214,7 +214,7 @@ class AgentService:
         return monitors
 
     def add(self, req: AgentRequest):
-        new_agent_num = self._get_newest_agent_number(req.saas_id)
+        new_agent_num = _get_newest_agent_number(req.saas_id)
         agent = Agent(saas_id=req.saas_id, agent_num=new_agent_num, agent_name=req.agent_name, out_id=req.out_id,
                       agent_pwd=req.agent_password, agent_type=req.agent_type, phone_num=req.phone_number,
                       distribute=req.distribute, agent_state=req.agent_state)