Fix key generation function #54
Description
Functions like generate_ed25519_bip32 are broken in the same way they were broken in Jormungandr input-output-hk/js-chain-libs#59
I think the curve25519-dalek package was updated maybe 1-2 months ago and it may have fixed this issue, but I've never bothered updating the dependency in our serialization lib because it would be kind of ugly to do. Ugly because the dependency on curve25519-dalek exists inside Jormungandr and instead of copying the cryptography into our codebase, we instead made Jormungandr a dependency.
To bump the version, you would have to change it in Jormungandr and fix all the issues in Jormungandr before then upgrading our lib so it's probably easier to tackle #47 first