Päivitetään postgres-volumen polku

[tomuli]

Postgres 18:n data-volumen polku vaihtui aikaisemmista versioista. Devissä käytössä jo 18, päivitetään polku jotta devauskanta säilyy konttien käynnistysten yli.

https://hub.docker.com/_/postgres#pgdata

Important Change: the PGDATA environment variable of the image was changed to be version specific in PostgreSQL 18 and above. For 18 it is /var/lib/postgresql/18/docker. Later versions will replace 18 with their respective major version (e.g., /var/lib/postgresql/19/docker for PostgreSQL 19.x). The defined VOLUME was changed in 18 and above to /var/lib/postgresql. Mounts and volumes should be targeted at the updated location. This will allow users upgrading between PostgreSQL major releases to use the faster --link when running pg_upgrade and mounting /var/lib/postgresql.