List contributors in GitHub release

[MarcoIeni]

Motivations

It's nice to give contributors some recognition for their work.
GitHub tags the author of the pr when you autogenerate a release from their UI. Release-plz should tag the authors as well.

Solution

For every PR number in the changelog, call this function to retrieve the pr author (and contributor?).

Than, in the release_body add a list of contributors:

## Contributors

- `@author1`
- `@author2`

Only if we are filling a github release. I don't know if gitea supports this.

[MarcoIeni]

Check https://github.com/github/contributors

[MarcoIeni]

We can use git-cliff github integration. To do this, set the ReleaseConfig in here:

release-plz/crates/release_plz_core/src/changelog.rs

Line 120 in ed8a348

}

(default_git_cliff_config fn).
Then, git-cliff will fetch github data, and will add it to the tera context.