consider replacing hex with const-hex for improved performance

[borngraced]

It looks like the hex crate (https://github.com/KokaKiwi/rust-hex) hasn’t been actively maintained for over three years. Since we work a lot with encoding and decoding, it might be worth considering a switch to the const-hex crate (https://github.com/DaniPopes/const-hex) instead, mainly for the performance improvements

[onur-ozkan]

Some dependencies don’t need active maintenance as their implementation relies on strict standards (e.g., md5). But still, I’m quite impressed by the performance difference between hex and const-hex; I think it’s worth trying out!