开启https代理后,websocket代理会被关闭

#### 平台：`Linux Centos7.6`
#### Anyproxy版本：`4.1.2`
#### 期望结果：`能同时代理https和wss请求`
#### 问题描述：
- 开启https代理后,代理wss请求就会出现如下日志,proxy ws closed..
- 只开启ws代理: anyproxy --ws-intercept 则可以正常代理
#### 执行日志:
```
0|proxy | [AnyProxy Log][2021-06-02 10:15:13]: proxy ws closed with code: 1006 and reason:
0|proxy | [AnyProxy Log][2021-06-02 10:15:13]: original ws closed with code: 1001 and reason: Unexpected server response: 500
0|proxy | [AnyProxy Log][2021-06-02 10:15:14]: received https CONNECT request ws.xxx.com
0|proxy | [AnyProxy Log][2021-06-02 10:15:14]: will forward to local https server
```

No source file or test is named. Reproduce on Linux CentOS 7.6 with AnyProxy 4.1.2, comparing `anyproxy --ws-intercept` alone with HTTPS proxying enabled, and inspect the HTTPS CONNECT and WebSocket handling associated with the logged 500 response. Done means HTTPS and WSS requests can be proxied simultaneously without the WebSocket closing.

Written by the indexing model from the issue text.