Incompatible with latest packaging (and thus latest Nixpkgs) #549
Description
Previously, when packaging.versions.parse was passed an invalid version (which are common in Nixpkgs as a result of unstable-YYYY-MM-DD versions) it would return an instance of the deprecated LegacyVersion class. LegacyVersion was removed in packaging 22.0. Nixpkgs recently updated packaging, meaning mach-nix gives an InvalidVersion error when it tries to parse Nixpkgs versions.