remove unused file.

src/DotNetCore.CAP/Dashboard/Monitoring/StateHistoryDto.cs

@@ -1,13 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace DotNetCore.CAP.Dashboard.Monitoring
-{
-    public class StateHistoryDto
-    {
-        public string StateName { get; set; }
-        public string Reason { get; set; }
-        public DateTime CreatedAt { get; set; }
-        public IDictionary<string, string> Data { get; set; }
-    }
-}