fix supabase-postgresql volume

[ak4zh]

I just noticed bitnami images uses a different path /bitnami/postgresql for the postgres data and not the standard /var/lib/postgresql/data.
This fixes the bitnami based supabase-postgres app which currently has incorrect volume mapped, so anyone with the current one will loose data on container reboot.

The bug was introduced in #993

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[githubsaturn]

Thanks!