Fix sample file for WrapAspNetCoreSession (#34783)

WrapAspNetCoreSession was changed to AddWrappedAspNetCoreSession in version 1.3.0 of SystemWebAdapters
Pull Request: dotnet/systemweb-adapters#424
1.3.0 Version Notes: https://github.com/dotnet/systemweb-adapters/releases/tag/v1.3.0

Author: NSHenry

aspnetcore/migration/inc/samples/wrapped/Program.cs

@@ -8,7 +8,7 @@
         options.RegisterKey<int>("test-value");
         options.RegisterKey<SessionDemoModel>("SampleSessionItem");
     })
-    .WrapAspNetCoreSession();
+    .AddWrappedAspNetCoreSession();
 // </snippet_WrapAspNetCoreSession>
 
 var app = builder.Build();