Bump Microsoft.NET.Test.Sdk from 16.8.3 to 16.9.1

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 16.8.3 to 16.9.1.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v16.8.3...v16.9.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

Tests/Directory.Build.props

@@ -6,7 +6,7 @@
     <PackageReference Include="coverlet.collector" PrivateAssets="All" Version="3.0.3">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.1" />
     <PackageReference Include="Moq" Version="4.16.0" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" PrivateAssets="All" Version="2.4.3">