fix: 画面比例改变无法立即生效，删除冗余代码

lib/plugin/pl_player/controller.dart

@@ -81,7 +81,6 @@ class PlPlayerController {
 
   final Rx<String> _direction = 'horizontal'.obs;
 
-  Rx<bool> videoFitChanged = false.obs;
   final Rx<BoxFit> _videoFit = Rx(BoxFit.contain);
   final Rx<String> _videoFitDesc = Rx('包含');
 
@@ -106,7 +105,6 @@ class PlPlayerController {
   Timer? _timerForShowingVolume;
   Timer? _timerForGettingVolume;
   Timer? timerForTrackingMouse;
-  Timer? videoFitChangedTimer;
 
   // final Durations durations;
 
@@ -1028,7 +1026,6 @@ class PlPlayerController {
     _timerForGettingVolume?.cancel();
     timerForTrackingMouse?.cancel();
     _timerForSeek?.cancel();
-    videoFitChangedTimer?.cancel();
   }
 
   // 记录播放记录
@@ -1079,7 +1076,6 @@ class PlPlayerController {
       _timerForGettingVolume?.cancel();
       timerForTrackingMouse?.cancel();
       _timerForSeek?.cancel();
-      videoFitChangedTimer?.cancel();
       // _position.close();
       _playerEventSubs?.cancel();
       // _sliderPosition.close();

lib/plugin/pl_player/view.dart

@@ -223,6 +223,7 @@ class _PLVideoPlayerState extends State<PLVideoPlayer>
       children: <Widget>[
         Obx(
           () => Video(
+            key: ValueKey(_.videoFit.value),
             controller: videoController,
             controls: NoVideoControls,
             pauseUponEnteringBackgroundMode: !enableBackgroundPlay,