Upstream changelog for Bohdi updates

[LecrisUT]

Description

Have an option to use the upstream's release notes when the koji build's Release == 1, i.e. the Version has changed, not the Release.

Benefit

I've occasionally seen well formatted (markdown-like) release notes in the Discover app. It would be nice to have the packit generated notes have a similar format. Not sure what the format is supposed to be for that, maybe: It's just markdown copy-pasted in

**Changelog**
```
# Markdown formatted text?
```

Example

https://bodhi.fedoraproject.org/updates/FEDORA-2024-2ffe03eaa6

Participation

• I am willing to submit a pull request for this issue. (Packit team is happy to help!)

[lachmanfrantisek]

Hi @LecrisUT , thanks for the suggestion.

Even though we currently mimic the behaviour of Bodhi (for Rawhide), this makes a lot of sense. Especially for stable releases. We've just discussed this within a team and a new action to (re)define the output might be the possible solution. (And similarly to the specfile changelog, we can provide various sources (e.g. specfile changelog and upstream changelog) in the form of an env. var.