fix(pnpm): extract engine constraint

[RahulGautamSingh]

Changes

• extract pnpm version from engines field in package.json

Context

• pnpm constraints causing `ERR_PNPM_UNSUPPORTED_ENGINE` #21928

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[rarkins]

Does it fix the reproduction?

[RahulGautamSingh]

Does it fix the reproduction?

Reproduction: https://github.com/RahulGautamSingh-testing/renovate-issue-21926
Yes
There is an artifact error but it is a diff one which is caused by my system (I am trying to resolve it)

[renovate-release]

🎉 This PR is included in version 35.73.2 🎉

The release is available on:

• GitHub release
• 35.73.2

Your semantic-release bot 📦🚀

[aaronadamsCA]

Hey, I'm sorry to report this didn't entirely resolve the issue. Here is a fresh reproduction:

https://github.com/nisheretail/renovate-issue-21928-again/pulls

So far I've only succeeding in recreating the issue on the pnpm upgrade branch, however in my repositories I'm seeing the failure on multiple (but not all!) branches.

I can create a new discussion in an hour or so once I've figured out the missing detail in the reproduction.