🚨(pylint) make pylint work and fix issues found

Pylint was not installed and wrongly configured. After making
it work, we fix all the issues found so it can be added to our
CI requirements.

src/backend/core/factories.py

@@ -2,19 +2,13 @@
 """
 Core application factories
 """
-import hashlib
-import json
-import random
-from datetime import datetime, timedelta, timezone
-
 from django.conf import settings
 from django.contrib.auth.hashers import make_password
-from django.utils import timezone as django_timezone
 
 import factory.fuzzy
 from faker import Faker
 
-from core import enums, models
+from core import models
 
 fake = Faker()