merge netstandard into main (#26)

* #23

* #23 "Newtonsoft.Json" Version="10.0.2"

* owin

* AspNetCore

* Fix appveyor build

* fix start/stop in untitests

src/WireMock.Net/Validation/Check.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Reflection;
 using JetBrains.Annotations;
@@ -12,7 +11,7 @@ using JetBrains.Annotations;
 // Copied from https://github.com/aspnet/EntityFramework/blob/dev/src/Shared/Check.cs
 namespace WireMock.Validation
 {
-    [ExcludeFromCodeCoverage]
+    // [ExcludeFromCodeCoverage]
     [DebuggerStepThrough]
     internal static class Check
     {