dev-python/pygit2 just dropped Python 2 support entirely. Since git-deps is Python 2-only, its presence is going to prevent users from upgrading and prevent us from removing the old version once the new one is stable.
If the package supports py3, please add it. If it doesn't, I will last rite it on the judgement day.
Also, this package hasn't seen a single keyworded ebuild since 2016. If you think it's useful, please add something people can actually install on their production systems.