Bump Microsoft.NET.Test.Sdk from 16.9.1 to 16.9.4 (#82)

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 16.9.1 to 16.9.4.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v16.9.1...v16.9.4)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

src/Directory.Build.props

@@ -34,7 +34,7 @@
   </PropertyGroup>
 
   <ItemGroup Condition="$(IsTestProject)">
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.4" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.console" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" />