Commit Cargo.lock

[tennox]

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 it's basically required 😋

[tennox]

I have the nixpkgs PR ready: NixOS/nixpkgs@master...tennox:nixpkgs:task-keeper
but I would only submit it after this is merged, for simplicity.

I also did not manage to get all the dependencies set up which would be needed for the tests to succeed 😞 - so I disabled tests when building the nix package for now. (fair enough)

[tennox]

I have submitted the nixpkgs PR in a way that works without this:
NixOS/nixpkgs#236516
but I'd still recommend that & like if this gets merged :)

[tennox]

Closed in favor of a clean PR:
#5