Remove unused interface

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/ICompositeModelBinder.cs

@@ -1,12 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-namespace Microsoft.AspNetCore.Mvc.ModelBinding
-{
-    /// <summary>
-    /// Represents an aggregate of <see cref="IModelBinder"/> that delegates to one of the instances for model binding.
-    /// </summary>
-    public interface ICompositeModelBinder : IModelBinder
-    {
-    }
-}