[feature request] Add sha256 object format support

[linsein]

According https://git-scm.com/docs/BreakingChanges.html , Git 3.0 will make sha256 default object format algorithm.
According https://www.phoronix.com/news/Git-3.0-Release-Talk-2026, Git 3.0 might be released by the end of 2026.

After a short look, I found we only have sha1 support. I think we should do some preparatory work first.

[linsein]

@unknwon Is this under consideration?
I am willing to use my spare time to do this.

[unknwon]

@unknwon Is this under consideration? I am willing to use my spare time to do this.

Hey @linsein yes! When you do, please work against v2 branch 🙏 i am doing a lot break changes there, but i think that’s better place.

[unknwon]

I am also in Discord jc_unknwon if you hit ideas need bounce around.