[Bilibili] fix bilibili 4k
diff --git a/src/you_get/extractors/bilibili.py b/src/you_get/extractors/bilibili.py
index 94e5479f65..7ea626f89d 100644
--- a/src/you_get/extractors/bilibili.py
+++ b/src/you_get/extractors/bilibili.py
@@ -62,7 +62,7 @@ def bilibili_headers(referer=None, cookie=None):
 
     @staticmethod
     def bilibili_api(avid, cid, qn=0):
-        return 'https://api.bilibili.com/x/player/playurl?avid=%s&cid=%s&qn=%s&type=&otype=json&fnver=0&fnval=16' % (avid, cid, qn)
+        return 'https://api.bilibili.com/x/player/playurl?avid=%s&cid=%s&qn=%s&type=&otype=json&fnver=0&fnval=16&fourk=1' % (avid, cid, qn)
 
     @staticmethod
     def bilibili_audio_api(sid):

B站的playurl API加了一个参数 fourk=1 时才会输出4K的播放地址，否则不显示。

bilibili has changed their playurl api, we should add fork=1 to the url params or it will not output the 4k url.