fix hsl path error

[4ft35t]

https://video.twimg.com/ext_tw_video/1566002757923848192/pu/pl/462x480/g1pv3QLgyc_Y99Wn.m3u8?container=fmp4

#EXTM3U
#EXT-X-VERSION:6
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-TARGETDURATION:3
#EXT-X-PLAYLIST-TYPE:VOD
#EXT-X-MAP:URI="/ext_tw_video/1566002757923848192/pu/vid/0/0/462x480/-criYBRHZjA2HPch.mp4"
#EXTINF:3.000,
/ext_tw_video/1566002757923848192/pu/vid/0/3000/462x480/wK8SSMXT4F1Xtbz7.m4s
#EXTINF:3.000,
/ext_tw_video/1566002757923848192/pu/vid/3000/6000/462x480/CryAYDTcfcB_XD2b.m4s
#EXTINF:3.000,
/ext_tw_video/1566002757923848192/pu/vid/6000/9000/462x480/H0bzl3PJdOT-8JPe.m4s
#EXTINF:3.000,
/ext_tw_video/1566002757923848192/pu/vid/9000/12000/462x480/oSs_OD_XjbmBn1hI.m4s
#EXTINF:2.200,
/ext_tw_video/1566002757923848192/pu/vid/12000/14200/462x480/1Gj-0OiFZufH4Cde.m4s
#EXT-X-ENDLIST

download with error

Exception: GET https://video.twimg.com/ext_tw_video/1566002757923848192/pu/pl/462x480//ext_tw_video/1566002757923848192/pu/vid/0/0/462x480/-criYBRHZjA2HPch.mp4 http响应: 404错误

the correct url is https://video.twimg.com/ext_tw_video/1566002757923848192/pu/vid/0/0/462x480/-criYBRHZjA2HPch.mp4

fix with urljoin