Fix code analysis violation after .NET 7 SDK update

Author: commonsensesoftware

src/Client/test/Asp.Versioning.Http.Client.Tests/TestServer.cs

@@ -7,11 +7,28 @@ namespace Asp.Versioning.Http;
 internal sealed class TestServer : HttpMessageHandler
 {
     private readonly HttpResponseMessage response;
+    private bool disposed;
 
     public TestServer() => response = new( HttpStatusCode.OK );
 
     public TestServer( HttpResponseMessage response ) => this.response = response;
 
     protected override Task<HttpResponseMessage> SendAsync( HttpRequestMessage request, CancellationToken cancellationToken ) =>
         Task.FromResult( response );
+
+    protected override void Dispose( bool disposing )
+    {
+        if ( disposed )
+        {
+            return;
+        }
+
+        base.Dispose( disposing );
+        disposed = true;
+
+        if ( disposing )
+        {
+            response.Dispose();
+        }
+    }
 }