Adds a version check when using --use-pnp

[arcanis]

This PR ensures that users of --use-pnp are using at least the 1.12 release, which is the first one supported by create-react-app.

Ref #5255

[jimthedev]

This won't work when they are using a nightly version of yarn since semver will throw.

https://repl.it/@jimthedev/IgnorantOutgoingActivemovie

You can handle this in the catch by parsing it a second time after popping off everything after the '.' in the nightly yarn version.

[jimthedev]

Looks like semver.gte('1.13.0-20181006.0202', '1.12.0', { loose:true }) might do it.