Add id field in amend lesson patch mutation

aleksis/apps/chronos/frontend/components/AmendLesson.vue

@@ -166,7 +166,7 @@ export default {
       };
     },
     transformPatchData(item) {
-      let { id, __typename, cancelled, ...patchItem } = item;
+      let { __typename, cancelled, ...patchItem } = item;
       return {
         ...patchItem,
         // Normalize cancelled, v-checkbox returns null & does not

aleksis/apps/chronos/schema/__init__.py

@@ -107,7 +107,7 @@ class AmendLessonBatchPatchMutation(DatetimeTimezoneMixin, DjangoBatchPatchMutat
     class Meta:
         model = LessonEvent
         permissions = ("chronos.edit_substitution_rule",)
-        only_fields = ("subject", "teachers", "groups", "rooms", "cancelled", "comment")
+        only_fields = ("id", "subject", "teachers", "groups", "rooms", "cancelled", "comment")
 
     @classmethod
     def before_save(cls, root, info, input, updated_objects):  # noqa: A002