Feature Request: Allow `-` as a Shortcut for `@{-1}` in `git diff`

[tao lv <thebookofunknowable@xxxxxxxxx>]

Hi,

I would like to request a feature for `git diff`: to allow the use of
`-` as a shortcut for `@{-1}`. Currently, `git merge` and `git
checkout` both support using `-` as a shortcut for `@{-1}`, and I hope
this functionality can be extended to `git diff` as well.

Thank you for considering this request.

Best regards