Update Microsoft.NET.Test.Sdk requirement from 16.8.* to 16.9.*

Updates the requirements on [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) to permit the latest version.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v16.8.0...v16.9.1)

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

Author: dependabot-preview[bot]

src/SampleApps/SampleApp.Classic.Tests/SampleApp.Classic.Tests.csproj

@@ -10,7 +10,7 @@
 	<ItemGroup>
 		<PackageReference Include="Appveyor.TestLogger" Version="2.0.0" />
 		<PackageReference Include="coverlet.msbuild" Version="3.0.*" />
-		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.*" />
+		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.*" />
 		<PackageReference Include="NUnit" Version="3.13.1" />
 		<PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
 		<PackageReference Include="Moq" Version="4.16.0" />

src/Simplify.Web.Tests/Simplify.Web.Tests.csproj

@@ -13,7 +13,7 @@
 	<ItemGroup>
 		<PackageReference Include="Appveyor.TestLogger" Version="2.0.0" />
 		<PackageReference Include="coverlet.msbuild" Version="3.0.*" />
-		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.*" />
+		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.*" />
 		<PackageReference Include="Moq" Version="4.16.*" />
 		<PackageReference Include="NUnit" Version="3.13.*" />
 		<PackageReference Include="NUnit3TestAdapter" Version="3.17.*" />