plugins.twitch: fix call_subdomain (#2958)
plugins.twitch: fix call_subdomain (#2958)

Fixes #2751
chhe/streamlink,melmorabity/streamlink,beardypig/streamlink,streamlink/streamlink,chhe/streamlink,beardypig/streamlink,streamlink/streamlink,gravyboat/streamlink,melmorabity/streamlink,bastimeyer/streamlink,bastimeyer/streamlink,gravyboat/streamlink