fix: volume path for PostgreSQL in docker-compose

[ItzDerock]

Attempting to deploy with the current docker-compose yielded:

Error response from daemon: failed to create task for container: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: error mounting "/.../postgres" to rootfs at "/var/lib/postgresql/data": change mount propagation through procfd: open o_path procfd: open /var/lib/docker/overlay2/.../merged/var/lib/postgresql/data: no such file or directory: unknown

With pgautougrade v18, the mount point has changed:

Then you have to adjust your volume mount from /var/lib/postgresql/data to /var/lib/postgresql. pgautoupgrade will look there for an old Postgres installation, and move the data into the new expected structure.

Root cause is docker-library/postgres#1259 that enforces a new data directory structure with Postgres v18+. Previously, your Postgres data and the corresponding PGDATA pointed to /var/lib/postgresql/data. With Postgres v18+, it is /var/lib/postgresql/MAJOR/docker. The Docker team also placed a symlink from /var/lib/postgresql/data to /var/lib/postgresql causing the error messages above.

https://github.com/pgautoupgrade/docker-pgautoupgrade/blob/main/README.md#error-message-when-mounting-data-to-varlibpostgresqldata-on-postgres-v18