Migrated all Test projects to ASP.NET Core 6.0

While the OnTopic library won't be upgraded to require .NET 6, the `Test` projects are intended for internal testing, and should reflect the latest version that we expect clients to be using. This won't affect the library itself.

Author: JeremyCaney

OnTopic.AspNetCore.Mvc.IntegrationTests/OnTopic.AspNetCore.Mvc.IntegrationTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net5.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 

OnTopic.AspNetCore.Mvc.Tests/OnTopic.AspNetCore.Mvc.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net5.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 

OnTopic.Tests/OnTopic.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net5.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <IsPackable>false</IsPackable>
     <NoWarn>CS1591</NoWarn>
   </PropertyGroup>