plugins.viasat: Update URL regex.
plugins.viasat: Update URL regex.

Resolves #773.

fishscene/streamlink,Saturn/livestreamer,programming086/livestreamer,gravyboat/streamlink,chrippa/livestreamer,gravyboat/streamlink,gtmanfred/livestreamer,chrippa/livestreamer,jtsymon/livestreamer,chhe/livestreamer,wlerin/streamlink,Dobatymo/livestreamer,intact/livestreamer,beardypig/streamlink,lyhiving/livestreamer,Klaudit/livestreamer,Saturn/livestreamer,caorong/livestreamer,wolftankk/livestreamer,streamlink/streamlink,back-to/streamlink,bastimeyer/streamlink,charmander/livestreamer,intact/livestreamer,mmetak/streamlink,okaywit/livestreamer,derrod/livestreamer,gtmanfred/livestreamer,jtsymon/livestreamer,flijloku/livestreamer,programming086/livestreamer,chhe/streamlink,derrod/livestreamer,mmetak/streamlink,flijloku/livestreamer,Masaz-/livestreamer,fishscene/streamlink,charmander/livestreamer,melmorabity/streamlink,Feverqwe/livestreamer,chhe/livestreamer,wolftankk/livestreamer,hmit/livestreamer,javiercantero/streamlink,okaywit/livestreamer,javiercantero/streamlink,bastimeyer/streamlink,sbstp/streamlink,Dobatymo/livestreamer,Masaz-/livestreamer,lyhiving/livestreamer,Feverqwe/livestreamer,chhe/streamlink,caorong/livestreamer,beardypig/streamlink,back-to/streamlink,ethanhlc/streamlink,streamlink/streamlink,ethanhlc/streamlink,Klaudit/livestreamer,melmorabity/streamlink,blxd/livestreamer,blxd/livestreamer,wlerin/streamlink,hmit/livestreamer,sbstp/streamlink