fix lint errors

archivebox/core/settings.py

@@ -6,7 +6,6 @@ import re
 import logging
 
 from pathlib import Path
-from datetime import datetime
 from django.utils.crypto import get_random_string
 
 from ..config import (                                                          # noqa: F401

archivebox/core/wsgi.py

@@ -7,7 +7,6 @@ For more information on this file, see
 https://docs.djangoproject.com/en/2.1/howto/deployment/wsgi/
 """
 
-import os
 
 from archivebox.config import setup_django
 setup_django(in_memory_db=False, check_db=True)