Removing unused tests file.

Ix.NET/Source/System.Interactive.Async.Tests/AsyncTests.Exceptions.cs

@@ -1,16 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the Apache 2.0 License.
-// See the LICENSE file in the project root for more information. 
-
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using Xunit;
-
-namespace Tests
-{
-    public partial class AsyncTests
-    {
-    }
-}