Remove .NET Framework tests

Author: RehanSaeed

Tests/Schema.NET.Test/Schema.NET.Test.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup Label="Build">
-    <TargetFrameworks>netcoreapp2.2;net461;net472</TargetFrameworks>
+    <TargetFrameworks>netcoreapp2.2</TargetFrameworks>
     <CodeAnalysisRuleSet>../../MinimumRecommendedRulesWithStyleCop.ruleset</CodeAnalysisRuleSet>
     <IsPackable>false</IsPackable>
     <LangVersion>latest</LangVersion>
@@ -13,8 +13,6 @@
 
   <ItemGroup Label="Package References">
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.1.1" />
-    <!-- See https://github.com/Microsoft/dotnet/tree/master/releases/reference-assemblies -->
-    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" PrivateAssets="All" Version="1.0.0-preview.2" />
     <PackageReference Include="Moq" Version="4.11.0" />
     <PackageReference Include="StyleCop.Analyzers" PrivateAssets="all" Version="1.1.118" />
     <PackageReference Include="xunit" Version="2.4.1" />