cargo: Move nix-test directly under dev-dependencies
cargo: Move nix-test directly under dev-dependencies

berkowski/nix,carllerche/nix-rust,kamalmarhubi/nix-rust,carllerche/nix-rust,geofft/nix-rust,posborne/rust-nix,posborne/rust-nix,berkowski/nix,geofft/nix-rust,carllerche/nix-rust,Susurrus/nix,asomers/nix,berkowski/nix,posborne/rust-nix,Susurrus/nix,nix-rust/nix,nikklassen/nix-rust,MarkusJais/nix-rust,kamalmarhubi/nix-rust,geofft/nix-rust,nikklassen/nix-rust,xd009642/nix,asomers/nix,kamalmarhubi/nix-rust,nix-rust/nix,Susurrus/nix,MarkusJais/nix-rust,nikklassen/nix-rust,MarkusJais/nix-rust,xd009642/nix,xd009642/nix