Upgrade to yarn 4

[wpears]

Testing

• Pull
• corepack enable
• yarn && yarn run build
• Try adding/removing dependencies. This should work as expected

[anselmbradford]

This is the .yarnrc.yml I landed on in cfpb/design-system#1916

enableGlobalCache: false

enableHardenedMode: true

enableMirror: true

enableOfflineMode: true

enableTelemetry: false

nodeLinker: node-modules

yarnPath: .yarn/releases/yarn-4.3.0.cjs

IIRC this is built off the defaults. FWIW the default is to put the cache in .yarn/cache. Is this something we want to do here? If not, I should probably change the cache directory in 1916.

[wpears]

@anselmbradford I don't think we'll need enableHardenedMode generally, and instead of defaulting to offlinemode (which seems not quite what it says on the tin), I've set the appropriate env var to disable network access in CI altogether.