解决PieChart的Legend中多了serie的问题

Assets/XCharts/Scripts/UI/Internal/BaseChart_API.cs

@@ -144,8 +144,12 @@ namespace XCharts
         /// <param name="show">whether to show this serie</param>
         /// <returns>the added serie</returns>
         public virtual Serie AddSerie(string serieName, SerieType type, bool show = true)
+        {
+            if(type != SerieType.Pie)
             {
                 m_Legend.AddData(serieName);
+            }
+            
             return m_Series.AddSerie(serieName, type);
         }