Fix test result filename in task `Invoke_Pester_Tests_v5`

[johlju]

Pull Request

Pull Request (PR) description

Fixed

• The task Invoke_Pester_Tests_v5 generated a unexpected filename for the test results, compared to the Pester 4 task. Fixes #355

Task list

• [x] The PR represents a single logical change. i.e. Cosmetic updates should go in different PRs.
• [x] Added an entry under the Unreleased section of in the CHANGELOG.md as per format.
• [x] Local clean build passes without issue or fail tests (build.ps1 -ResolveDependency).
• [ ] Documentation added/updated in README.md.
• [ ] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [ ] Unit tests added/updated. See DSC Community Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• [x] New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[codecov[bot]]

Codecov Report

Merging #356 (31edbfb) into main (bcab266) will increase coverage by 0%. The diff coverage is 0%.

@@         Coverage Diff         @@
##           main   #356   +/-   ##
===================================
  Coverage    28%    28%           
===================================
  Files        40     40           
  Lines      2163   2162    -1     
===================================
  Hits        608    608           
+ Misses     1555   1554    -1     

Impacted Files	Coverage Δ
.build/tasks/Invoke-Pester.pester.build.ps1	0% <0%> (ø)