🚨(backend) fix linting issues after upgrading

The last upgrades introduced some linting issues.
This commit fixes them.

src/backend/impress/celery_app.py

@@ -1,4 +1,5 @@
 """Impress celery configuration file."""
+
 import os
 
 from celery import Celery

src/backend/impress/settings.py

@@ -9,6 +9,7 @@ https://docs.djangoproject.com/en/3.1/topics/settings/
 For the full list of settings and their values, see
 https://docs.djangoproject.com/en/3.1/ref/settings/
 """
+
 import json
 import os