Optimized code for phpstan. (#1881)

Author: limingxinleo

src/Server.php

@@ -43,7 +43,7 @@
 use Swoole\Http\Response as SwooleResponse;
 use Swoole\Server as SwooleServer;
 use Swoole\WebSocket\CloseFrame;
-use Swoole\Websocket\Frame;
+use Swoole\WebSocket\Frame;
 use Swoole\WebSocket\Server as WebSocketServer;
 
 class Server implements MiddlewareInitializerInterface, OnHandShakeInterface, OnCloseInterface, OnMessageInterface