Yarn update

[chaffeqa]

1.16.0 is out and looks to have some nice improvements.

(sorry about the ping if this is not necc, don't know if there was an official solution after reading #547 but if not, than just getting this on the radar manually seems ok to me).

PS: ❤️ how on top of node updates you guys are... really makes things exciting for the community to be able to access the newer tech so quickly. thx!

[SimenB]

We update yarn on new releases of node so we don't change any versions from under people's feet, see https://github.com/nodejs/docker-node/blob/bbb46b714097cd3115a819d86192e1473365a84b/CONTRIBUTING.md#version-updates

You can update yourself by following this process: https://github.com/nodejs/docker-node/blob/bbb46b714097cd3115a819d86192e1473365a84b/docs/BestPractices.md#upgradingdowngrading-yarn