Add back thumbnail extraction to legacy webpage extraction method

Author: devoxin

main/src/main/java/com/sedmelluq/discord/lavaplayer/source/vimeo/VimeoAudioSourceManager.java

@@ -147,7 +147,9 @@ private AudioTrack loadTrackFromPageContent(String trackUrl, String content) thr
             (long) (config.get("clip").get("duration").get("raw").as(Double.class) * 1000.0),
             trackUrl,
             false,
-            trackUrl
+            trackUrl,
+            config.get("thumbnail").get("src").text(),
+            null
         ), this);
     }