fix: Initials do not display on notification avatars (#5803)

app/models/Revision.ts

@@ -1,9 +1,10 @@
 import { computed } from "mobx";
 import { isRTL } from "@shared/utils/rtl";
-import BaseModel from "./BaseModel";
 import User from "./User";
+import Model from "./base/Model";
+import Relation from "./decorators/Relation";
 
-class Revision extends BaseModel {
+class Revision extends Model {
   id: string;
 
   documentId: string;
@@ -20,8 +21,7 @@ class Revision extends BaseModel {
   /** HTML string representing the revision as a diff from the previous version */
   html: string;
 
-  createdAt: string;
-
+  @Relation(() => User)
   createdBy: User;
 
   /**