Fix save AuthorBalance

apps/payment/models.py

@@ -1,11 +1,12 @@
+from constance import config
+from paymentwall import Pingback
+from polymorphic.models import PolymorphicModel
+
 from django.db import models
 from django.contrib.auth import get_user_model
 from django.contrib.postgres.fields import ArrayField, JSONField
 from django.core.validators import RegexValidator
-
+from django.utils.timezone import now
-from constance import config
-from paymentwall import Pingback
-from polymorphic.models import PolymorphicModel
 
 from apps.course.models import Course
 from apps.school.models import SchoolSchedule