Bump Newtonsoft.Json, Microsoft.NET.Test.Sdk and Microsoft.NETFramework.ReferenceAssemblies (dotnet#1831)

Author: dependabot[bot]

Directory.Packages.props

@@ -9,7 +9,7 @@
     <PackageVersion Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.SourceGenerators.Testing" Version="1.1.2" />
     <PackageVersion Include="Microsoft.CodeAnalysis.PublicApiAnalyzers" Version="3.11.0-beta1.24219.2" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />