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[bot] <support@github.com>

Messages.Tests/Messages.Tests.csproj

@@ -14,7 +14,7 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore" Version="5.0.3" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="5.0.3" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="5.0.3" />
-    <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</PrivateAssets>