community/bareos: remove postgresql as dependency of bareos-dir init

Remove the strong dependency from postgresql in bareos-dir.initd

bareos-test:~# rc-status
 * Caching service dependencies ...
Service `bareos-dir' needs non existent service `postgresql'

Postgresql could be installed on another host, so better to know have a dependency from postgresql.

Gentoo follows the same approach: https://gitweb.gentoo.org/repo/gentoo.git/tree/app-backup/bareos/files/bareos-dir-21-r1.initd?id=2b77e1dbbace1692c94d943233c779b7494e00df