fix birthday nullable

Src/Dlhis.Entity/Basic/Entity/GainfoEntity.cs

@@ -84,7 +84,7 @@ public class GainfoEntity : SugarBaseEntity
     /// 生日
     /// </summary>
     [SugarColumn(IsNullable = true, ColumnDescription = "生日")]
-    public DateTime Birthday { get; set; }
+    public DateTime? Birthday { get; set; }
 
     /// <summary>
     /// 身份证地址

Src/Dlhis.Entity/Basic/Entity/GainfoSapEntity.cs

@@ -26,7 +26,7 @@ namespace Dlhis.Entity.Basic.Entity
         public string idno { get; set; }
         public string native { get; set; }
         public string sex { get; set; }
-        public DateTime birthday { get; set; }
+        public DateTime? birthday { get; set; }
         public string address { get; set; }
 
         public string postcode { get; set; }