Upgrade Pester to version 6

[liamjpeters]

PR Summary

Windows PowerShell CI tests were not pinned to a Pester version and so used the latest stable. This changed recently to v6 (well done on the release @nohwnd 🎉).

Windows PowerShell CI was broken - complaining of a missing -Pending parameter, which has been removed in v6.

Instead of just pinning the Windows PowerShell version to 5.7.1, the changes required for v6 compatibility were minimal, so those changes were made instead.

Claude and I used the v5-v6 migration guide and skill to update to v6.

I've now pinned the Windows PowerShell version in line with the tools/installPSResources.ps1 version - settling on the current 6.0.1. I Can't find a tidy way to specify the version once and have it used in both places. Open to suggestions if there's a good way.

Note: This does not do the Should -Be to Should-Be migration that is optional for this version change and documented here.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Change is not breaking
• Make sure all .cs, .ps1 and .psm1 files have the correct copyright header
• Make sure you've added a new test if existing tests do not effectively test the code changed and/or updated documentation
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: to the beginning of the title and remove the prefix when the PR is ready.

[Copilot]

Pull request overview

Updates the repo’s tooling, CI, and test suite to be compatible with (and pinned to) Pester v6, addressing Windows PowerShell CI failures caused by the removal of the -Pending parameter.

Changes:

• Pinned Pester to 6.0.1 in tooling (installPSResources.ps1) and Windows PowerShell CI (ci-test.yml).
• Migrated affected Pester tests from -Pending to -Skip for v6 compatibility.
• Updated README references to Pester v6 / minimum required Pester version.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tools/installPSResources.ps1	Bumps the pinned Pester version used by tooling installs to 6.0.1.
Tests/Rules/UseToExportFieldsInManifest.tests.ps1	Replaces -Pending usage with -Skip for Pester v6 compatibility.
Tests/Rules/UseIdenticalMandatoryParametersForDSC.tests.ps1	Replaces -Pending usage with -Skip for Pester v6 compatibility.
README.md	Updates documentation to reference Pester v6 and minimum required version.
.github/workflows/ci-test.yml	Pins Pester version in Windows PowerShell CI to avoid unintentional upgrades.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.