gsb: mark as broken

No active maintenance for several years; dependencies cannot be met.

(cherry picked from commit 1379baca94f3a14231811705ee7fb309571bad2b)
Signed-off-by: Domen Kožar <[e-mail]>

pkgs/games/gsb/default.nix

···
     license = licenses.unfree;
     maintainers = with maintainers; [ jcumming ];
     platforms = [ "x86_64-linux" "i686-linux" ] ;
+    broken = true;
   };
 
 }