fix: 修复候选重复添加问题

src/agent.c

@@ -487,7 +487,10 @@ void agent_process_stun_request(Agent* agent, StunMessage* stun_msg, Address* ad
             remote_candidate = &agent->remote_candidates[i];
             LOGI("Remote candidate already exists: %s:%d",
                  inet_ntoa(addr->sin.sin_addr), ntohs(addr->sin.sin_port));
-//            return;
+            agent_create_binding_response(agent, &msg, addr);
+            agent_socket_send(agent, addr, msg.buf, msg.size);
+            agent->binding_request_time = ports_get_epoch_time();
+            return;
             break;
           }
         }