Fix Sonarqube issues

src/WireMock.Net/Owin/Mappers/OwinResponseMapper.cs

@@ -7,8 +7,6 @@ using System.Threading.Tasks;
 using Newtonsoft.Json;
 using RandomDataGenerator.FieldOptions;
 using RandomDataGenerator.Randomizers;
-using WireMock.Exceptions;
-using WireMock.Handlers;
 using WireMock.Http;
 using WireMock.ResponseBuilders;
 using WireMock.Types;

src/WireMock.Net/Owin/WireMockMiddleware.cs

@@ -2,9 +2,7 @@ using System;
 using System.Threading.Tasks;
 using WireMock.Logging;
 using System.Linq;
-using System.Text.RegularExpressions;
 using WireMock.Matchers;
-using Newtonsoft.Json;
 using WireMock.Http;
 using WireMock.Owin.Mappers;
 using WireMock.Serialization;

src/WireMock.Net/Owin/WireMockMiddlewareOptions.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Concurrent;
-using System.Collections.ObjectModel;
 using WireMock.Handlers;
 using WireMock.Logging;
 using WireMock.Matchers;