remove unused code

src/DotNetCore.CAP/Models/CapQueue.cs

-// Copyright (c) .NET Core Community. All rights reserved.
-// Licensed under the MIT License. See License.txt in the project root for license information.
-
-namespace DotNetCore.CAP.Models
-{
-    public class CapQueue
-    {
-        public int MessageId { get; set; }
-
-        /// <summary>
-        /// 0 is CapSentMessage, 1 is CapReceivedMessage
-        /// </summary>
-        public MessageType MessageType { get; set; }
-    }
-}
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