minio is not recognized.

on nc install & update

The scripts does execute a [pgdump_all](https://github.com/zalando/postgres-operator/blob/master/docker/logical-backup/dump.sh#L24)

Hence it doesn't take into account this env var.
The command pgdump does understand it:
https://www.postgresql.org/docs/8.3/app-pgdump.html