fix(player): 使用雪碧图预热首帧兜底

lib/pages/player/widgets/seek_progress_bar.dart

@@ -41,7 +41,6 @@ class SeekProgressBar extends StatefulWidget {
     this.thumbnailService,
     this.spriteAxisService,
     this.episodeId,
-    this.posterUrl = '',
     this.thumbnailsUrl,
   });
 
@@ -57,7 +56,6 @@ class SeekProgressBar extends StatefulWidget {
   final PlaybackThumbnailService? thumbnailService;
   final SpriteThumbnailAxisService? spriteAxisService;
   final String? episodeId;
-  final String posterUrl;
   final String? thumbnailsUrl;
 
   @override
@@ -351,7 +349,6 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
                   spriteAxisService: widget.spriteAxisService,
                   thumbnailsUrl: widget.thumbnailsUrl,
                   episodeId: widget.episodeId!,
-                  posterUrl: widget.posterUrl,
                   position: previewPosition,
                   duration: video.duration,
                 ),