Fix values of amended lessons not being shown in form

aleksis/apps/chronos/frontend/components/calendar_feeds/details/LessonDetails.vue

@@ -259,9 +259,9 @@ export default {
     initPatchData() {
       return {
         id: this.selectedEvent.meta.id,
-        subject: this.selectedEvent.meta.subject?.id,
-        teachers: this.selectedEvent.meta.teachers.map((teacher) => teacher.id),
-        rooms: this.selectedEvent.meta.rooms.map((room) => room.id),
+        subject: this.selectedEvent.meta.subject?.id.toString(),
+        teachers: this.selectedEvent.meta.teachers.map((teacher) => teacher.id.toString()),
+        rooms: this.selectedEvent.meta.rooms.map((room) => room.id.toString()),
         cancelled: this.selectedEvent.meta.cancelled,
         comment: this.selectedEvent.meta.comment,
       };