ci: add pnpm to ignoreDeps

[btea]

Description

I think pnpm should be upgraded manually. For example, pnpm10 has made some changes to the default behavior, and some other configurations need to be added to keep it consistent with the previous default behavior.
https://github.com/pnpm/pnpm/releases/tag/v10.0.0

[sapphi-red]

I think the current config is fine. There's no problem with automatically upgrading minor / patch versions of pnpm. We need to apply some changes sometimes for major bumps, but a separate PR would be created by renovate in that case.

[btea]

Yeah, I noticed that renovate created a separate PR #19393 to update the pnpm major version. However, due to breaking changes in pnpm 10 for script execution, the test case failed.

At this point, someone needs to add additional configuration and modify the content of the PR. I think this is not as clear and accurate as someone manually updating and creating a PR.

However, it is OK to keep it as it is. I see that other patch and minor version updates also have a history of manual modification.