[v3] ci: lock pnpm version to 9

[traeok]

Proposed changes

Locks the pnpm version in CI to v9.

Release Notes

Milestone:

Changelog:

Types of changes

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• [x] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Updates to Documentation or Tests (if none of the other choices apply)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This checklist will be used as reference for both the contributor and the reviewer

• [x] I have read the CONTRIBUTOR GUIDANCE wiki
• [x] PR title follows Conventional Commits Guidelines
• [x] PR Description is included
• [ ] gif or screenshot is included if visual changes are made
• [ ] yarn workspace vscode-extension-for-zowe vscode:prepublish has been executed
• [x] All checks have passed (DCO, Jenkins and Code Coverage)
• [ ] I have added unit test and it is passing
• [ ] I have added integration test and it is passing
• [ ] There is coverage for the code that I have added
• [x] I have tested it manually and there are no regressions found
• [ ] I have added necessary documentation (if appropriate)
• [ ] Any PR dependencies have been merged and published (if appropriate)

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[traeok]

Turns out that pnpm v9.0.1 was released and it didn't propagate to the runners until some time after this commit was pushed/tested. It resolved an issue where pnpm install failed in CI when the lockfile could be changed. If it's okay with the team, I'd like to update this to lock the version to pnpm@9, as it would be consistent w/ other Zowe repos that lock the major version of the package manager (such as the CLI).