Describe the bug
During build phrase with pnpm-workspace.yaml in the root, buildpack skips pruning depedencies:

-----> Pruning devDependencies
       Skipping because pruning is not supported for pnpm workspaces (https://pnpm.io/cli/prune)

I assume, this is because prune command does not support recursive execution on a monorepo currently.

However, presence of pnpm-workspace.yaml doesn't mean that the project is using monorepo setup, as this file is main file used for pnpm configuration: see https://pnpm.io/settings

I think pruning happen be possible unless pnpm uses monorepo setup

To Reproduce
Steps to reproduce the behavior:

1. Create project with pnpm-workspace.yaml

Versions (please complete the following information):

• Heroku Stack: heroku-24
• Node Version: 24
• NPM or Yarn Version: pnpm 10.18.1
• Buildpack Version: latest

Additional context
N/A