added needed settings + fix missing import

core/models.py

@@ -1,5 +1,6 @@
 import datetime
 from collections import defaultdict
+from django.utils import timezone as tz
 from django.db import models
 
 # Create your models here.
@@ -66,7 +67,6 @@ both 'month' and 'year' keyword arguments")
 
         qs = self.get_queryset(month=month, year=year)
         data = self.calculate_data(qs)
-        print(qs, data)
         return qs, data