[feature request] support configuration of default branch name

[ChrisCarini]

Currently, this GHA assumes that the branch is named master and does not allow for any other branch name (ref: https://github.com/ActionwareIO/all-contributors-action/blob/master/src/git/pushAllChangesToGit.ts#L6 ). It would be great to extend this action to allow configuration of other branch names, such as main, which is the new default branch name for repos (see https://github.com/github/renaming ).