Downgrade to Postgres 15 (#392)

Postgres 16 not available on BTP, using 15 instead.

Follow-up to
#391

Author: mofterdinger

mta.yaml

@@ -82,7 +82,7 @@ resources:
       service: postgresql-db
       service-plan: standard
       config:
-        engine_version: "16"
+        engine_version: "15"
         multi_az: false
 
   - name: cf-logging

srv/src/main/resources/application.yaml

@@ -1,5 +1,5 @@
 ---
-my.bookshop.postgresImage: postgres:16
+my.bookshop.postgresImage: postgres:15
 
 cds:
   dataSource.csv:
@@ -26,4 +26,3 @@ spring:
 cds:
   dataSource:
     auto-config.enabled: false
-