Remove unused serialization functions

src/action/childchangepassword.ts

@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 Jonas Lochmann
+ * Copyright (C) 2019 - 2020 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -31,11 +31,6 @@ export class ChildChangePasswordAction extends ChildAction {
     this.password = password
   }
 
-  serialize = (): SerializedChildChangePasswordAction => ({
-    type: 'CHILD_CHANGE_PASSWORD',
-    password: this.password
-  })
-
   static parse = ({ password }: SerializedChildChangePasswordAction) => (
     new ChildChangePasswordAction({ password })
   )