appveyor: update config to fix builds on Python 3.3
appveyor: update config to fix builds on Python 3.3

wlerin/streamlink,wlerin/streamlink,chhe/streamlink,back-to/streamlink,chhe/streamlink,streamlink/streamlink,back-to/streamlink,javiercantero/streamlink,beardypig/streamlink,melmorabity/streamlink,gravyboat/streamlink,bastimeyer/streamlink,melmorabity/streamlink,javiercantero/streamlink,gravyboat/streamlink,beardypig/streamlink,bastimeyer/streamlink,streamlink/streamlink