Fixed #32366 -- Updated datetime module usage to recommended approach.

- Replaced datetime.utcnow() with datetime.now().
- Replaced datetime.utcfromtimestamp() with datetime.fromtimestamp().
- Replaced datetime.utctimetuple() with datetime.timetuple().
- Replaced calendar.timegm() and datetime.utctimetuple() with datetime.timestamp().

tests/foreign_object/tests.py

@@ -92,7 +92,7 @@ class MultiColumnFKTests(TestCase):
 
     def test_reverse_query_filters_correctly(self):
 
-        timemark = datetime.datetime.utcnow()
+        timemark = datetime.datetime.now(tz=datetime.timezone.utc).replace(tzinfo=None)
         timedelta = datetime.timedelta(days=1)
 
         # Creating a to valid memberships