Refresh PGP keys, e.g. when prolonging an expiration time

[FrostyX]

Creating this ticket after a discussion with @mcurlej.

There is already a DNF5 ticket which describes the issue in detail, please see
rpm-software-management/dnf5#1192

A step-by-step reproducer is described in my comment in the same issue:
rpm-software-management/dnf5#1192 (comment)

It is very important to get the issue fixed in DNF5 but at the same time, all of our users that currently report the issue, are experiencing it in DNF4. Would it be possible to get it fixed here as well, please? Otherwise, we would have to introduce some hacky workarounds into the Copr DNF plugin.