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 (https://github.com/NixOS/nixpkgs/pull/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.