packit: only use IoT relevant branches

[miabbott]

Since IoT uses a rolling stable ref, we don't need action on the n-1 "stable" branch in Fedora dist-git. (i.e. stable is currently F40, we don't need action on the F39 branch)

Packit has some aliases that let us narrow the scope of versions that the service will operate against. fedora-development targets the next major version of Fedora + Rawhide. fedora-latest-stable targets exactly one version (the latest version) of stable. See below:

>>> from packit.config.aliases import get_aliases
>>> get_aliases()['fedora-development']
['fedora-41', 'fedora-rawhide']
>>> get_aliases()['fedora-latest-stable']
['fedora-40']

[say-paul]

LGTM