API /commits author and commiter objects is empty in case of user.email is empty

[Vacxe]

Select Topic Area

Bug

Body

Reference: https://docs.github.com/en/rest/commits/commits?apiVersion=2022-11-28
Setup: git --global user.email is empty
Issue:
If user.email is empty then author and commiter going to be an empty objects

    ...
    "author": {},
    "committer": {},
..
  }

Fix suggestion:
Respond null or set field as optional.

[Vacxe]

See: danger/kotlin#249