Update solana-sdk dependency

[fasmat]

This updates the solana-sdk dependency. The currently used version is already quite old and dependabot cannot automatically update it to the most recent version.

[lrettig]

It looks like solana-sdk v2 is currently unreleased: https://github.com/solana-labs/solana/blob/master/CHANGELOG.md.

Shouldn't we stick with the latest stable release? Right now that's v1.17

[fasmat]

Updated to use the newest v1.17.x.

[fasmat]

Do we need the dependency on solana-sdk? As far as I can see we are only using it for creating ed25519 keys. Thats a big dependency for a relatively small task. We could use a smaller library like https://github.com/dalek-cryptography/curve25519-dalek, wdyt?

[lrettig]

Do we need the dependency on solana-sdk? As far as I can see we are only using it for creating ed25519 keys. Thats a big dependency for a relatively small task. We could use a smaller library like https://github.com/dalek-cryptography/curve25519-dalek, wdyt?

Yes, we appear to only be using it for key management and signatures. It is a big dependency for a small task. We anyway need to update smcli to support the new ledger app, so maybe we just do an overhaul at that time.