chore: downgrade pnpm to 9.12.0 to avoid renovate break

[Timeless0911]

Summary

Latest version of pnpm changed some behaviour, and the renovate generated PR will remove pnpmfileChecksum filed in lockfile which will cause no frozen lockfile error that breaks CI.

Related Issue

Checklist

• [ ] Tests updated (or not required).
• [ ] Documentation updated (or not required).

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[Timeless0911]

seems to do not solve this issue.