repo.blame should allow passing None as the rev parameter. #1835

This issue only affects the type hint given to the rev parameter, as passing None to the function does work and gives the expected behavior, which is running the git blame -p -- <file> command without a revision, which gives back the blame including changes to the local working directory that haven't been committed yet.

While the code works at runtime, language servers such as pylance give back an error, as None is not a valid type according to the type hints.