update version for database acceptance test

Author: markdboyd

ci/pipeline.yml

@@ -652,8 +652,8 @@ jobs:
                 CF_SPACE: ((development-tests-cf-space))
                 SERVICE_PLAN: micro-psql
                 DB_TYPE: postgres
-                OLD_VERSION: 15
-                NEW_VERSION: 18
+                OLD_VERSION: 15.1
+                NEW_VERSION: 18.3
                 ALLOW_MAJOR_VERSION_UPGRADE: true
 
             - task: smoke-tests-postgres-rotate-creds-replica
@@ -985,7 +985,7 @@ jobs:
                 CF_SPACE: ((staging-tests-cf-space))
                 SERVICE_PLAN: micro-psql
                 DB_TYPE: postgres
-                DB_VERSION: 17.3
+                DB_VERSION: 15.1
 
             - task: smoke-tests-postgres-update-micro-to-small
               file: aws-broker-app/ci/run-smoke-tests-db-updates.yml