Broken build

[SBoudrias]

Ref https://travis-ci.org/yeoman/yeoman.github.io/builds/213676907

We made a mistake in our deploy script yarn usage and it can modify the yarn.lock file. We need to use the flag to only install dependency without automatically bumping versions. Otherwise it'll fail the deploy as uncommitted files are present.

I'll fix later today, but I'm happy to merge a PR fixing this - it should be fairly simple.

[SBoudrias]

Actually, not sure we can do something as that's handled by Travis directly. Seems there's been a few discussion on the yarn project about changing the default behavior yarnpkg/yarn#570

Nothing actionnable on our end. I've bumped the dependencies. Build is green again.