Bump Microsoft.NET.Test.Sdk in /tests/PVOutput.Net.Tests

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 16.7.1 to 16.9.1.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v16.7.1...v16.9.1)

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

tests/PVOutput.Net.Tests/PVOutput.Net.Tests.csproj

@@ -18,7 +18,7 @@
 		  <PrivateAssets>all</PrivateAssets>
 		  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 		</PackageReference>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.1" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\PVOutput.Net\PVOutput.Net.csproj" />