add postgres

http-api/app/routes/enrollments/enroll.py

@@ -5,7 +5,6 @@ from http import HTTPStatus
 from aws_lambda_powertools.event_handler.api_gateway import Router
 from layercake.batch import BatchProcessor
 from layercake.dynamodb import (
-    DynamoDBCollection,
     DynamoDBPersistenceLayer,
 )
 from pydantic import BaseModel