Bump the tests group with 2 updates

Bumps the tests group with 2 updates: [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) and [xunit](https://github.com/xunit/xunit).


Updates `Microsoft.NET.Test.Sdk` from 17.8.0 to 17.9.0
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Changelog](https://github.com/microsoft/vstest/blob/main/docs/releases.md)
- [Commits](microsoft/vstest@v17.8.0...v17.9.0)

Updates `xunit` from 2.6.2 to 2.6.6
- [Commits](xunit/xunit@2.6.2...2.6.6)

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: tests
- dependency-name: xunit
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: tests
...

Signed-off-by: dependabot[bot] <[email protected]>

src/Tests/Tests.csproj

@@ -10,7 +10,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />
     <PackageReference Include="System.IO.Compression" Version="4.3.0" />
-    <PackageReference Include="xunit" Version="2.6.2" />
+    <PackageReference Include="xunit" Version="2.6.6" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.6" PrivateAssets="all" />
   </ItemGroup>