Launch yarn before linking to new peertube version
Launch yarn before linking to new peertube version

If yarn fails because we don't have the correct nodejs version, we want to know
earlier, so that we can upgrade nodejs without having a non-working
half-installed peertube instance.

Chocobozzz/PeerTube,Chocobozzz/PeerTube,Chocobozzz/PeerTube,Chocobozzz/PeerTube