AdfsDsc: Update AzurePipelines CI to use PowerShell 7 for Pester Tests

[X-Guardian]

Pull Request (PR) description

This PR update the CI to use PowerShell 7 for the HQRM and Unit Pester tests.

This Pull Request (PR) fixes the following issues

None

Task list

• [ ] Added an entry to the change log under the Unreleased section of the file CHANGELOG.md. Entry should say what was changed and how that affects users (if applicable), and reference the issue being resolved (if applicable).
• [ ] Resource documentation added/updated in README.md.
• [ ] Resource parameter descriptions added/updated in README.md, schema.mof and comment-based help.
• [ ] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [ ] Examples appropriately added/updated.
• [ ] Unit tests added/updated. See DSC Community Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• [ ] New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[codecov[bot]]

Codecov Report

Merging #44 (927be1b) into dev (2cb8372) will not change coverage. The diff coverage is n/a.

@@         Coverage Diff         @@
##            dev    #44   +/-   ##
===================================
  Coverage    98%    98%           
===================================
  Files        16     16           
  Lines      2061   2061           
===================================
  Hits       2025   2025           
  Misses       36     36