Update local dev environment to postgres 18 (#12236)

* Update local dev environment to postgres 18

Author: cdrini

compose.override.yaml

@@ -72,7 +72,7 @@ services:
       - ${OL_MOUNT_DIR:-.}:/openlibrary
 
   db:
-    image: postgres:${POSTGRES_VERSION:-9.3}
+    image: postgres:${POSTGRES_VERSION:-18.3}
     networks:
       - dbnet
     environment:
@@ -82,10 +82,9 @@ services:
     volumes:
       - ${OL_MOUNT_DIR:-.}:/openlibrary
       # Any files inside /docker-entrypoint-initdb.d/ will get run by postgres
-      # if the db is empty (which as of now is always, since we don't store the
-      # postgres data anywhere).
+      # if the db is empty (ie during first run).
       - ./docker/ol-db-init.sh:/docker-entrypoint-initdb.d/ol-db-init.sh
-      - ol-postgres:/var/lib/postgresql/data
+      - ol-postgres:/var/lib/postgresql
 
   covers:
     build: