Add author/contributor name to the changelogs

[pyrito]

Is your feature request related to a problem? Please describe.
Currently git-cliff does not parse out the author names and save them at the end of the changelog.

Describe the solution you'd like
Add an option to write out contributor names at the end of the changelog.

[pyrito]

@orhun this is something I could probably take on with some guidance code wise. I think we just need to parse out the contributor names and maintain them in a set.

[gautamprikshit1]

git-cliff/git-cliff-core/src/commit.rs

Line 118 in 77731ec

pub author: Signature,

I think this can be helpful

[PSeitz]

This can already be accessed via the template, e.g.

{% for group, commits in commits | group_by(attribute="group") %}
    ### {{ group | upper_first }}
    {% for commit in commits %}
        - {% if commit.breaking %}[**breaking**] {% endif %}{{ commit.message | upper_first }}\
        Author: {{ commit.author.name }}
    {% endfor %}
{% endfor %}\n

[orhun]

You can now achieve this with the GitHub integration.