Update license to unfree

pkgs/servers/serviio/default.nix

···
       Serviio is a free media server. It allows you to stream your media files (music, video or images)
       to any DLNA-certified renderer device (e.g. a TV set, Bluray player, games console) on your home network.
     '';
-    license = licenses.free;
+    license = licenses.unfree;
     maintainers = [ maintainers.thpham ];
     platforms = platforms.linux;
   };