Following the recent announcement of updates to the PostgreSQL database, we have updated Amazon RDS for PostgreSQL to support new PostgreSQL minor versions. This release contains security fixes, bug fixes and improvements done by the PostgreSQL community.  

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/10/amazon-rds-for-postgresql-supports-minor-version-115-1010-9615-9515-9424-adds-transportable-database-feature/