Revert "Add fish to nixos module list"

This reverts commit d7f5d00f0a7a73e3f7a837b741bae25814490e3b.

nixos/modules/module-list.nix

···
   ./programs/virtualbox-host.nix
   ./programs/wvdial.nix
   ./programs/freetds.nix
-  ./programs/fish/fish.nix
   ./programs/zsh/zsh.nix
   ./rename.nix
   ./security/apparmor.nix