alfred: 2018.0 -> 2018.1

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/alfred/versions.

These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 2018.1 with grep in /nix/store/2fj5i6zd4mp4asxchsig266lqz8acliv-alfred-2018.1
- directory tree listing: https://gist.github.com/64f566e02d8018fe290dc3db29fd7c7f