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] <[email protected]>

Author: dependabot-preview[bot]

csharp/Platform.RegularExpressions.Transformer.CSharpToCpp.Tests/Platform.RegularExpressions.Transformer.CSharpToCpp.Tests.csproj

@@ -11,7 +11,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.1" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" PrivateAssets="All" />
     <PackageReference Include="coverlet.collector" Version="3.0.3" PrivateAssets="All" />