pnpm versioning issue causes OOM during build

[raybellis]

Describe the bug
The package.json file requires PNPM version 10.18.0. If the globally installed version does not match this, the pnpm run build:etherpad phase appears to spawn an endless number of pnpm add pnpm@10.18.0 commands, eventually resulting in an out-of-memory situation.

To Reproduce
Steps to reproduce the behavior:

1. follow the build instructions, to the letter
2. See the system break

Expected behavior
A clean build

Screenshots

ERROR  Command failed with exit code 1: pnpm add pnpm@10.18.0 --loglevel=error --allow-build=@pnpm/exe --no-dangerously-allow-all-builds --config.node-linker=hoisted --config.bin=bin
For help, run: pnpm help add
ERROR  Command failed with exit code 1: pnpm add pnpm@10.18.0 --loglevel=error --allow-build=@pnpm/exe --no-dangerously-allow-all-builds --config.node-linker=hoisted --config.bin=bin
For help, run: pnpm help add
...
ad infinitum until memory is exhausted

Server (please complete the following information):

• Etherpad version: 2.5.1
• OS: FreeBSD 14.3
• Node.js version (node --version): v22.19.0
• npm version (npm --version): 11.6.0
• Is the server free of plugins: yes

Additional context
For now I've resolved this by forcibly installing v10.18.0 globally, i.e. npm install -g pnpm@10.18.0

A better fix (IMHO) would be to change the packageManager field in package.json so that it will accept 10.18.0 or later.