[Task] Update Yarn and Node

[billhimmelsbach]

Found this bug when trying to run tests locally:

This bug is caused by running on an old version of node on older versions of yarn, which has been fixed in later updates. Updating to the latest version of yarn fixes this issue (the DS did it earlier), but v4 of yarn also requires at least node 18. We should at least update from node 16 to node 18 anyway for the engine, since it's at EOL. We could also update all the way to node 20, or even 22 if we're ok with it not being a LTS release for a few months. We can probably wait till post-mvp for that change.

I want to check to make sure this is ok with how the DDD is written before updating though.

Current behavior

• yarn is at v3
• node is at v16

Expected behavior

• yarn is at v4
• node is at 18, maybe even 20/22 post-mvp if we're ok not being on a LTS release for a few months