Linting

* validate python formatting on every build with Ruff
* fix lint warnings

application/celeryconfig.py

@@ -1,7 +1,8 @@
 import os
+
 broker_url = os.getenv("CELERY_BROKER_URL")
 result_backend = os.getenv("CELERY_RESULT_BACKEND")
 
 task_serializer = 'json'
 result_serializer = 'json'
-accept_content = ['json']
+accept_content = ['json']