Allow using blake2 hash

[RubenKelevra]

Currently, the sha2-256 hash is hardcoded

As the blake2 hash is much faster with enhanced safety comparable to sha3, it would be neat if there's an option to switch to it.

[sameer]

Hello, unfortunately git-lfs-ipfs must use sha256. This is because LFS itself only supports sha256: https://github.com/git-lfs/git-lfs/blob/main/docs/spec.md

It might be possible to use a different hash but that would require changing the way things are tracked from the file level to the repo level.