Eliminate unused Types

Author: CharliePoole

.github/workflows/NUnitConsoleAndEngine.CI.yml

@@ -37,6 +37,7 @@ jobs:
           dotnet-version: |
             3.1.x
             6.0.x
+            7.0.x
             8.0.100
 
       - name: 🔧 Install dotnet tools

src/NUnitEngine/nunit.engine.core.tests/Internal/Backports/PathTests.cs

@@ -8,9 +8,11 @@ namespace NUnit.Engine.Communication.Transports
     /// The ITestAgentTransport interface is implemented by a
     /// class providing communication for a TestAgent.
     /// </summary>
-    public interface ITestAgentTransport : ITransport
+    public interface ITestAgentTransport
     {
         TestAgent Agent { get; }
         ITestEngineRunner CreateRunner(TestPackage package);
+        bool Start();
+        void Stop();
     }
 }

src/NUnitEngine/nunit.engine.core.tests/Internal/Backports/TupleTests.cs

@@ -9,7 +9,9 @@
 using NUnit.Engine.Internal.FileSystemAccess;
 using NUnit.Engine.Internal.FileSystemAccess.Default;
 using System.Linq;
+#if NET462
 using NUnit.Engine.Internal.Backports;
+#endif
 
 namespace NUnit.Engine.Extensibility
 {