opt: 播放页路由监听销毁时移除订阅

lib/pages/video/detail/view.dart

@@ -271,6 +271,7 @@ class _VideoDetailPageState extends State<VideoDetailPage>
       plPlayerController!.dispose();
     }
     videoPlayerServiceHandler.onVideoDetailDispose();
+    VideoDetailPage.routeObserver.unsubscribe(this);
     // _lifecycleListener.dispose();
     showStatusBar();
     // _animationController.dispose();