Update Test Bot File and Gateway

- Gateway now can be closed **safely**.

- test bot config now exports `TOKEN`.

src/models/gateway.ts

@@ -180,6 +180,10 @@ class Gateway {
     this.websocket.onclose = this.onclose.bind(this)
     this.websocket.onerror = this.onerror.bind(this)
   }
+
+  close () {
+    this.websocket.close(1000)
+  }
 }
 
 export { Gateway }

src/test/config.ts.sample

@@ -1 +1,2 @@
 const TOKEN = ''
+export { TOKEN }