add updated CCPO request index columns

atst/models/request.py

@@ -1,7 +1,6 @@
 from sqlalchemy import Column, func, ForeignKey
 from sqlalchemy.types import DateTime
 from sqlalchemy.orm import relationship
-import pendulum
 
 from atst.models import Base
 from atst.models.types import Id
@@ -145,7 +144,7 @@ class Request(Base):
 
         last_submission = first_or_none(_is_submission, reversed(self.status_events))
         if last_submission:
-            return pendulum.instance(last_submission.time_created)
+            return last_submission.time_created
         return None
 
     @property