Suggest pnpm in missing modules error

Before you open this issue, please complete the following tasks:

* [x] use the search bar at the top of the page to search this repository for similar issues or discussions that have already been opened.
* [x] if you are looking for help from the gulp team or community, open a [discussion](https://github.com/gulpjs/gulp/discussions).
* [x] if you think there is a problem with the plugin you're using, open a [discussion](https://github.com/gulpjs/gulp/discussions).
* [x] if you think there is a bug in our code, open this issue.

### What were you expecting to happen?

If node_modules aren't present and `pnpm-lock.yaml` is present, gulp-cli should say "Try running: pnpm install"

### What actually happened?

It defaults to suggesting "npm install". The issue is [this line](https://github.com/gulpjs/gulp-cli/blob/master/index.js#L172).

### Please give us a sample of your gulpfile
N/A

### Terminal output / screenshots

### Please provide the following information:
N/A - This happens in any environment.

### Additional information
N/A

node_modules がない場合に gulp-cli が npm install を提案する index.js の 172 行目付近から始めます。issue に記載された package-manager の lockfile の条件を確認し、pnpm-lock.yaml があるプロジェクトでは pnpm install の提案が表示され、既存の fallback は変更されないことを検証します。

索引モデルが issue の本文から書いたものです。