Bump Microsoft.NET.Test.Sdk from 16.7.1 to 16.9.1

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>

Ve.DotNet.Tests/Ve.DotNet.Tests.csproj

@@ -14,7 +14,7 @@
 
     <ItemGroup>
         <PackageReference Include="MeCab.DotNet" Version="0.0.40" />
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.1" />
         <PackageReference Include="MSTest.TestAdapter" Version="2.2.3" />
         <PackageReference Include="MSTest.TestFramework" Version="2.1.1" />
         <PackageReference Include="coverlet.collector" Version="3.0.3" />