chore(deps): update PowerShell Test v7.4 to v7.4.20

[github-actions]

Bumps tests/test-pwsh-7.4.props from v7.4.19 to v7.4.20.

Auto-generated by a dependency updater.

Changelog

Commits between v7.4.19 and v7.4.20

• Merged PR 41499: [release/v7.4.20] Make NET8 default for all pipelines
• Merge commit 'f48474921ee0cdfa9927dba7993d94057931fd15'
• Merged PR 41488: [release/v7.4.20] Resolve GitHub mirror conflict
• [release/v7.4.20] Enable early .NET builds in APIScan (#27955)
• Merged PR 41481: Use C# 12.0 for v7.4.20
• Merged PR 41480: Merged PR 41091: Fix feed authentication for gallery
• Merge commit '84e116ecade9c9e514f4d24e18f0794d616d87ac'
• [release/v7.4.20] Merged PR 41075: Map credential provider variable as it is a secret (#27961)
• Merge commit 'fc6a8747274aabe7e967fc2e2862086d33eaa4b0'
• [release/v7.4.20] Use Azure CLI for early-access feed token (#27954)
• Merged PR 41468: Update 'ThirdPartyNotices.txt' for v7.4.20
• Merge commit '9f81dae83da83079d00171eee6884d45a56b48e7'
• Update 7.4 changelog for v7.4.20 (#27949)
• Merged PR 41466: [release/v7.4.20] Fix potential pointer allocation issue in PdhHelper
• Merged PR 41465: [release/v7.4.20] Harden Copy-Item -FromSession against remote path traversal
• Merged PR 41464: [release/v7.4.20] Fix remote prompt spoofing for SecureString/PSCredential arrays
• Merged PR 41451: [release/v7.4.20] Update branch for release
• [release/v7.4.20] Use Custom Validation Policy for vPack Pipeline (#27913)
• [release/v7.4.20] Fix install dotnet for non early access release (#27926)
• [release/v7.4.20] Fix OneBranch output variables for early .NET jobs (#27920)
• [release/v7.4.20] Use .NET SDK and NuGet feed early access for build, package and release pipelines (#27910)
• Merged PR 41207: Add codesign policy file for vPack