0x should include a Cargo.lock file

[AndersonTorres]

Hello!
I am Anderson Torres, a Nixpkgs maintainer.

I found this package a time ago, and I decided to package it (NixOS/nixpkgs#186235).

By reading the documentation about packaging Rust apps, it cites the Cargo Handbook, that recommends including a Cargo.lock file into the version control.