Make committer email configurable

[n0toose]

Hello, I would like to ask whether you could consider making the email address used to associate commits made using this Action configurable instead of it being hard-coded.

I would do it myself, but I unfortunately don't really know a lot about TypeScript or GitHub Actions.

This would be useful for projects that wish to use their own infrastructure (or do so at a later point in time) or branding using a GitHub Actions-compatible implementation that utilizes a tool like act. Such an example would be e.g. Gitea or Forgejo, the latter of which started using this action recently: https://codeberg.org/forgejo/docs/issues/18#issuecomment-1062390