fix: group entity functies bereikbaar

backend/src/entities/assignments/group.entity.ts

@@ -1,8 +1,13 @@
 import { Entity, ManyToMany, ManyToOne, PrimaryKey } from '@mikro-orm/core';
 import { Assignment } from './assignment.entity.js';
 import { Student } from '../users/student.entity.js';
+import { GroupRepository } from '../../data/assignments/group-repository.js';
 
-@Entity()
+@Entity({
+    repository: () => {
+        return GroupRepository;
+    },
+})
 export class Group {
     @ManyToOne({
         entity: () => {