Invalid pnpm version is (not) fetched during firebsae deployment

[dsl101]

Describe the bug

Bug is described here from the firebase-tools side. @dominics identified this code as problematic, as the npm version (9.14.3) does not exist as a downloadable release.

Additional context

How are you using GCP buildpacks?

• pack and the gcr.io/buildpacks/builder
• Cloud Functions
• Cloud Run
• Cloud Build
• App Engine Standard
• App Engine Flex
• Firebase App Hosting

Did this used to work?
Yes

What language is your project primarily written in?
Javascript

The errors from the client cli:

i  functions: updating Node.js 20 (1st Gen) function authUserOnCreate(us-central1)...
Build failed: installing pnpm: (error ID: e462f501):
downloading pnpm: (error ID: 44d6210b):
fetching https://github.com/pnpm/pnpm/releases/download/v9.14.3/pnpm-linux-x64 returned HTTP status: 404; Error ID: d34422e2

Successful mitigation by including an explicit pnpm version in the functions package.json:

  "engines": {
    "node": "20",
    "pnpm": "9.14.2"
  },