Update index.js

保证库调用方式的兼容性

Author: spotiyu

src/index.js

@@ -1,13 +1,8 @@
 'use strict';
 
 const client = require('./client');
-const STT = require('./stt');
-const Packet = require('./packet');
-const Logger = require('./logger');
+client.STT = require('./stt');
+client.Packet = require('./packet');
+client.Logger = require('./logger');
 
-module.exports = {
-    client,
-    STT,
-    Packet,
-    Logger,
-};
+module.exports = client