Change back Updates.Images to ICollection

CoviDok/Data/Model/Update.cs

@@ -14,7 +14,7 @@ namespace CoviDok.Data.Model
         public Role SenderRole { get; set; }
         public string Content { get; set; }
         public DateTime CreatedDate { get; set; }
-        public List<string> Images { get; set; }
+        public ICollection<string> Images { get; set; }
         public Update()
         {
             Images = new List<string>();