How to upgrade Yarn version

I followed this documentation to specify my Node and Yarn versions in the package.json. I’d like my app to build using Yarn 2+, but when I check the build logs it fails. Does the app platform only support Yarn 1?

Buildpack: buildpack-stack=ubuntu-22

package.json:

"engines": {
        "node": "18.x",
        "yarn": "^4.0.1"
    },

build log:

[2023-12-03 15:06:05] ╭──────────── git repo clone ───────────╼
[2023-12-03 15:06:05] │  › fetching app source code
[2023-12-03 15:06:05] │ => Selecting branch "main"
[2023-12-03 15:06:07] │ => Checking out commit "c5b243c2e69acb46cb2b2a96f77c1bb9ccf4fa15"
[2023-12-03 15:06:07] │ 
[2023-12-03 15:06:07] │  ✔ cloned repo to /workspace
[2023-12-03 15:06:07] ╰────────────────────────────────────────╼
[2023-12-03 15:06:07] 
[2023-12-03 15:06:07]  › configuring build-time app environment variables:
[2023-12-03 15:06:07]      YARN_PRODUCTION FIRESTORE_SERVICE_ACCOUNT AUTH_GITHUB_CLIENT_SECRET LOGGER_GRAFANA_API_KEY AUTH_SUPERTOKENS_API_KEY
[2023-12-03 15:06:07] 
[2023-12-03 15:06:07]  › configuring custom build command to be run at the end of the build:
[2023-12-03 15:06:07]    │ yarn prod:build
[2023-12-03 15:06:07] 
[2023-12-03 15:06:07] ╭──────────── buildpack detection ───────────╼
[2023-12-03 15:06:07] │  › using Ubuntu 22.04 stack
[2023-12-03 15:06:07] │ Detected the following buildpacks suitable to build your app:
[2023-12-03 15:06:07] │ 
[2023-12-03 15:06:07] │    heroku/nodejs-engine   v0.5.2  
[2023-12-03 15:06:07] │    digitalocean/node      v0.3.6  (Node.js)
[2023-12-03 15:06:07] │    digitalocean/procfile  v0.0.4  (Procfile)
[2023-12-03 15:06:07] │    digitalocean/custom    v0.1.2  (Custom Build Command)
[2023-12-03 15:06:07] │ 
[2023-12-03 15:06:07] │ For documentation on the buildpacks used to build your app, please see:
[2023-12-03 15:06:07] │ 
[2023-12-03 15:06:07] │    Node.js  v0.3.6  https://do.co/apps-buildpack-node
[2023-12-03 15:06:07] ╰─────────────────────────────────────────────╼
[2023-12-03 15:06:07] 
[2023-12-03 15:06:07] ╭──────────── app build ───────────╼
[2023-12-03 15:06:07] │ ---> Node.js Buildpack
[2023-12-03 15:06:07] │ ---> Installing toolbox
[2023-12-03 15:06:07] │ ---> - jq
[2023-12-03 15:06:08] │ ---> - yj
[2023-12-03 15:06:09] │ ---> Getting Node version
[2023-12-03 15:06:09] │ ---> Resolving Node version
[2023-12-03 15:06:12] │ ---> Downloading and extracting Node v18.19.0
[2023-12-03 15:06:20] │ ---> Parsing package.json
[2023-12-03 15:06:22] │ 
[2023-12-03 15:06:22] │  ! Yarn v2+ is not supported on this App Platform stack. Please visit our documentation for more information on supported versions and stacks: https://do.co/apps-buildpack-node
[2023-12-03 15:06:22] │ 
[2023-12-03 15:06:22] │ ERROR: failed to build: exit status 1
[2023-12-03 15:06:22] │ 
[2023-12-03 15:06:22] │ 
[2023-12-03 15:06:22] │ For documentation on the buildpacks used to build your app, please see:
[2023-12-03 15:06:22] │ 
[2023-12-03 15:06:22] │    Node.js  v0.3.6  https://do.co/apps-buildpack-node
[2023-12-03 15:06:22] │ 
[2023-12-03 15:06:22] │  ✘ build failed
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