Foreman Maintain

Description of problem:
Ohai!

Recently, foreman-maintain gained dependencies on the PostgreSQL client and (on EL8) the nftables package, but these are not part of https://github.com/theforeman/foreman_maintain/blob/master/extras/foreman_protector/foreman-protector.whitelist

It's a bit of a chicken-and-egg problem, as during the upgrade, the config of the protector plugin from 0.8.31 is used (and that doesn't have those new deps), so I think ideally we would backport the fix to "all" relevant branches.

Version-Release number of selected component (if applicable):

How reproducible:
100%

Steps to Reproduce:
1. install satellite 6.10 with external DB (so that there is no psql client on the machine)
2. try to install maintain for 6.11

Actual results:
Error, because PostgreSQL client can't be installed

Expected results:
Installable

Additional info: