Shellify does not place newlines at the end of shell.nix and flake.nix files

[coillteoir]

Hi, currently shellify won't end files with newlines. The general standard is to end files with a newline, since git, and other tools will mark it as a warning.

[danielrolls]

@coillteoir's, patch has been merged and released. It will slowly make it's way onto stackage and nixpkgs. In the mean time it's possible to get this behavior by running from master here. Closing as complete.