Update Program.cs (#36103)

I think most of the other top-level programs/templates call `Run()` instead of `await RunAsync()`. For the sake of consistency we should probably use `Run`.

Related to the evolution of templates with .NET 6:

- #33853

src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/Program.cs

@@ -7,4 +7,4 @@
     })
     .Build();
 
-await host.RunAsync();
+host.Run();