Fix lint issues, minor celery app update

Author: matiasb

django_tasks/backends/celery/app.py

@@ -4,7 +4,6 @@
 
 from django_tasks.task import DEFAULT_QUEUE_NAME
 
-
 # Set the default Django settings module for the 'celery' program.
 django_settings = os.environ.get('DJANGO_SETTINGS_MODULE')
 if django_settings is None:
@@ -19,3 +18,5 @@
 app.config_from_object('django.conf:settings', namespace='CELERY')
 
 app.conf.task_default_queue = DEFAULT_QUEUE_NAME
+
+app.autodiscover_tasks()

django_tasks/backends/celery/backend.py

@@ -1,12 +1,17 @@
 from typing import TypeVar
 
-from typing_extensions import ParamSpec
-
 from celery import shared_task
+from celery.app import default_app
 from celery.local import Proxy as CeleryTaskProxy
+from typing_extensions import ParamSpec
+
 from django_tasks.backends.base import BaseTaskBackend
 from django_tasks.task import Task, TaskResult
 
+if not default_app:
+    from django_tasks.backends.celery.app import app as celery_app
+    celery_app.set_default()
+
 
 T = TypeVar("T")
 P = ParamSpec("P")