Remove dummy tests

CliFx.Tests.Dummy/Program.cs

@@ -1,21 +0,0 @@
-using System.Globalization;
-using System.Threading.Tasks;
-
-namespace CliFx.Tests.Dummy
-{
-    public static class Program
-    {
-        public static Task<int> Main(string[] args)
-        {
-            // Set culture to invariant to maintain consistent format because we rely on it in tests
-            CultureInfo.DefaultThreadCurrentCulture = CultureInfo.InvariantCulture;
-            CultureInfo.DefaultThreadCurrentUICulture = CultureInfo.InvariantCulture;
-
-            return new CliApplicationBuilder()
-                .AddCommandsFromThisAssembly()
-                .UseDescription("Dummy program used for E2E tests.")
-                .Build()
-                .RunAsync(args);
-        }
-    }
-}