chore(deps): simplify how some dependencies are fetched

[noctisatrae]

Summary of the changes

• edited config.toml to use a git repository with a commit hash and a package specifier (telling Cargo where to look for stuff)
• cargo.lock was updated when I pulled dependencies after my changes
• updated instructions in the README.

Goals

• Improve developer experience
• According to the Rust standard, crates should include everything in order to be built

Hope this will be useful <3

[noctisatrae]

I was browsing around and saw that #184 was in the work, feel free to close this if you don't need it then :)

[noctisatrae]

I watched the changes made in #225 and wanted to further simplify your pipeline. Now that Cargo handles the download of the repo & the version, your build actions should be much easier to write. I hope this is useful :)

EDIT: would you like me to make changes to the GitHub actions to delete the checkout steps? (and also the Dockerfile)

[christopherwxyz]

Malachite packages were published. Probably can close this PR.

[noctisatrae]

You're right, my PR should be edited to account for the release of Malachite. However, some changes are still relevant today: eth-signature-verifier is still imported with a relative path.

I can understand this is not the priority ATM tho!

[noctisatrae]

This PR is a mess I need to maintain as the changes drop but I've been underwater lately ;)