https://github.com/minio/sha256-simd#drop-in-replacement

Currently when profiling building images, almost 95%+ of cpu time (and the CPU time is ~= wall time) is on sha256 operations. sha256-simd claims to make this much faster, which in turn could make image building faster.

I haven't proven it will actually have real impacts. Opening this to track + get some early feedback on if this is something that would be an acceptable dependency.