oscar: Switch factorio -> factorio-space-age

For a new version that hasn't hit `nixpkgs-unstable` yet, use this
instead of the second change below:

    # (import (fetchTarball "https://github.com/NixOS/nixpkgs/archive/<commit hash>.tar.gz") {
    #   config.allowUnfree = true;
    # }).factorio-space-age

oscar/configuration.nix

@@ -124,8 +124,8 @@
   home-manager.users.chandler = { pkgs, ... }: {
 
     nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
-      "factorio-alpha"
       "discord"
+      "factorio-space-age"
     ];
 
     home.packages = with pkgs; [
@@ -164,7 +164,7 @@
 
       # Unfree:
       discord
-      factorio
+      factorio-space-age
     ];
 
     programs.thunderbird.enable = true;