Hi,
I had the same problem and a workaround for me was to download all files in psychopy/psychopy/iohub/devices/eyetracker/hw/pupil_labs/pupil_core at release · psychopy/psychopy · GitHub (for example via DownGit) and copy them to my psychopy installation at /psychopy/iohub/devices/eyetracker/hw/pupil_labs/pupil_core/