Support CITATION.cff file

[moble]

I really appreciate this action — particularly the automatic version bumping behavior. Recently, the CITATION.cff file has become a de facto standard for allowing code to be cited, and I'm seeing it used more and more among julia package creators. Unfortunately, it also has two fields that need to be updated with each new version: the version and date-released fields. It would be truly awesome if this action could also update those fields if it finds a CITATION.cff file.

Though my javascript skills are weak, I think this is a PR I might be able to pull off. My only question is how to handle changes to both files. It looks like octokit won't allow a single commit without help from some plugin like this one. Would it be better to just do multiple commits or use such a plugin?