Commit Cargo.lock

[tennox]

The original PR was from the wrong branch and mingled with other changes, so I created this clean one.

For reference, here's the gist:

This is recommended for binaries (as opposed to libraries)
-> see https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html

Also, I want to submit this to nixpkgs, and for that also helps 😋

I have submitted the nixpkgs PR with a manually added Cargo.lock:
NixOS/nixpkgs#236516
but I'd still recommend that & like if this gets merged, as it creates fragmentation :)

[tennox]

@linux-china I've merged your latest master & had to update rust toolchain, thus this PR now also updates the devenv to rust v1.84.0-nightly

Would be great if you could merge it, as it enables both:

• install via nix docs: add install instructions for nix #13
• and makes adding it to nixpkgs easier (no need to commit Cargo.lock there and keep it up-to-date manually)