Trimui updated the brick firmware to 1.1.0, and with that they updated RetroArch, changed up Saturn stuff, and changed up Nintendo 64 stuff. I've done my best to reflect those changes in this latest update.
You can also find the 1.1.0 firmware update here for convenience.
Updating:
If you are updating, it should be just fine to overwrite everything with the contents of onestep.7z. The PICO 8 file will have to be renamed again, and you may want to make a backup of your RetroArch retroarch.cfg file.