Bump Microsoft.NET.Test.Sdk from 15.5.0 to 16.6.1

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 15.5.0 to 16.6.1.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v15.5.0...v16.6.1)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

test/json-ld.net.tests/json-ld.net.tests.csproj

@@ -21,7 +21,7 @@
 
   <ItemGroup>
     <PackageReference Include="coverlet.msbuild" Version="2.8.1" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.6.1" />
     <PackageReference Include="xunit" Version="2.3.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
     <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />