update yarn to 1.6.0

[pdeva]

title says all

[SimenB]

We don't change the yarn version for released images, they are updated on new node releases. See https://github.com/nodejs/docker-node/blob/master/CONTRIBUTING.md#version-updates

[chenrui333]

Any info on the yarn upgrade? I dont think I understand the release process. Thanks!

cc @LaurentGoderre

[LaurentGoderre]

We keep the Node part of the image as immutable as possible. This means that we only change yarn version when a new version is released (except in the case of security releases).

It will most likely be updated when nodejs/node#21593 lands

[chenrui333]

I see, thanks for the heads-up.