Updated to C# 12

UnitTests/AspNetCore/Security/BasicAuthentication/BasicAuthenticationMiddlewareTests.cs

@@ -9,6 +9,7 @@ using System.Threading.Tasks;
 using AMWD.Common.AspNetCore.Security.BasicAuthentication;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Primitives;
+using Microsoft.Net.Http.Headers;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 
@@ -156,12 +157,16 @@ namespace UnitTests.AspNetCore.Security.BasicAuthentication
 			var requestHeaderMock = new Mock<IHeaderDictionary>();
 			foreach (var header in _requestHeaders)
 			{
+				var strVal = new StringValues(header.Value);
 				requestHeaderMock
 					.Setup(h => h.ContainsKey(header.Key))
 					.Returns(true);
 				requestHeaderMock
 					.Setup(h => h[header.Key])
-					.Returns(header.Value);
+					.Returns(strVal);
+				requestHeaderMock
+					.Setup(h => h.TryGetValue(header.Key, out strVal))
+					.Returns(true);
 			}
 
 			var requestMock = new Mock<HttpRequest>();
@@ -174,6 +179,11 @@ namespace UnitTests.AspNetCore.Security.BasicAuthentication
 			responseHeaderMock
 				.SetupSet(h => h[It.IsAny<string>()] = It.IsAny<StringValues>())
 				.Callback<string, StringValues>((key, value) => _responseHeadersCallback[key] = value);
+#pragma warning disable CS0618
+			responseHeaderMock
+				.SetupSet(h => h.WWWAuthenticate)
+				.Callback((value) => _responseHeadersCallback[HeaderNames.WWWAuthenticate] = value);
+#pragma warning restore CS0618
 
 			var responseMock = new Mock<HttpResponse>();
 			responseMock