[infra] Update DefaultVersions.props package versions

[github-actions]

Caution

Protected files were modified in this change.
This pull request is in request_review mode and requires explicit human scrutiny before merge.

Protected files: Directory.Packages.props

Automated update of toolset package versions in DefaultVersions.props.

Summary of Changes

Property	Package ID	Old Version	New Version	Source
MicrosoftNETTestSdkVersion	Microsoft.NET.Test.Sdk	18.0.1	18.8.0-release-26310-106	dotnet-eng feed
MicrosoftVSSDKBuildToolsDefaultVersion	Microsoft.VSSDK.BuildTools	17.14.2120	18.9.820	nuget.org
MicrosoftTestPlatformVersion	Microsoft.TestPlatform	18.0.1	18.7.0	nuget.org
XUnitAnalyzersVersion	xunit.analyzers	2.0.0-pre.51	2.0.0-pre.56	nuget.org
XUnitV3Version	xunit.v3	4.0.0-pre.81	4.0.0-pre.128	nuget.org
MicrosoftTestingPlatformVersion	Microsoft.Testing.Platform	2.2.3	2.3.1	nuget.org
MSTestVersion	MSTest	4.2.3	4.3.0	nuget.org

Directory.Packages.props was also updated to keep XUnitV3Version, XUnitAnalyzersVersion, and MicrosoftTestingPlatformVersion in sync (per the comment in that file).

Packages needing mirroring

⚠️ The build may fail for packages not yet available on the dotnet-public feed until they are mirrored. See Documentation/MirroringPackages.md for instructions.

Package ID	Version
Microsoft.NET.Test.Sdk	18.8.0-release-26310-106
Microsoft.VSSDK.BuildTools	18.9.820
Microsoft.TestPlatform	18.7.0
xunit.analyzers	2.0.0-pre.56
xunit.v3	4.0.0-pre.128
Microsoft.Testing.Platform	2.3.1
MSTest	4.3.0

Note: For xunit packages, mirroring must be done manually per Documentation/update-xunit.md.

Generated by 📦 Update DefaultVersions.props · sonnet46 1.6M · ◷

[github-actions]

Protected files were modified in this pull request and require manual scrutiny before merge.

Please verify that each protected-file change is intentional, policy-compliant, and safe:

• Protected files: Directory.Packages.props