Refactor endpoint tests

Replace force_login calls with login call from client class in setUp

src/newsreader/news/collection/utils.py

@@ -2,6 +2,7 @@ from datetime import datetime
 
 from django.utils import timezone
 
+import pytz
 import requests
 
 from requests.exceptions import RequestException
@@ -15,7 +16,8 @@ def build_publication_date(dt, tz):
         published_parsed = timezone.make_aware(naive_datetime, timezone=tz)
     except (TypeError, ValueError):
         return None, False
-    return published_parsed, True
+
+    return published_parsed.astimezone(pytz.utc), True
 
 
 def fetch(url):