Mark StringValueTypeBase serializable

framework/src/Volo.Abp.Validation/Volo/Abp/Validation/StringValues/StringValueTypeBase.cs

@@ -1,7 +1,9 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 
 namespace Volo.Abp.Validation.StringValues
 {
+    [Serializable]
     public abstract class StringValueTypeBase : IStringValueType
     {
         public virtual string Name => ValueValidatorAttribute.GetName(GetType());