notification mark as read api modified for clear all, list sorting set to updated at field, added same field

notifications/models.py

@@ -18,6 +18,7 @@ class Notification(models.Model):
     data = models.JSONField(default=dict, blank=True, null=True)
     is_read = models.BooleanField(default=False)
     created_at = models.DateTimeField(default=timezone.now)
+    updated_at = models.DateTimeField(auto_now=True)
 
     def __str__(self):
         """ string representation """