Replace deprecated macOS 11 image with 13 in CI

[fflaten]

PR Summary

MacOS 11 image is deprecated in Azure Pipeline and Github will remove it in June 2024. Github manages runners for Azure Pipelines so it'll likely be removed soon after.

Bumping to MacOS 12 + 13 as a hotfix while waiting on stable macOS 14 image.

PR Checklist

• [x] PR has meaningful title
• [x] Summary describes changes
• [x] PR is ready to be merged
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• [ ] Tests are added/update (if required)
• [ ] Documentation is updated/added (if required)

[fflaten]

/backport to rel/5.6.x

[github-actions[bot]]

Started backporting to rel/5.6.x: https://github.com/pester/Pester/actions/runs/9177877243