add note about AsGeoJSON issue

src/django_oapif/decorators.py

@@ -10,6 +10,9 @@
 from django_oapif.urls import oapif_router
 
 from .filters import BboxFilterBackend
+
+# this should be be switched to contrib
+# when https://code.djangoproject.com/ticket/34882#ticket is fixed
 from .functions import AsGeoJSON
 
 

src/django_oapif/functions.py

@@ -1,6 +1,9 @@
 from django.contrib.gis.db.models import functions
 from django.db import models
 
+# see https://code.djangoproject.com/ticket/34882#ticket
+# and https://github.com/django/django/pull/17320
+
 
 class AsGeoJSON(functions.AsGeoJSON):
  output_field = models.TextField()