It’s this issue redux: Working directory change with 2020.1 and later?
If you want a temporary fix, at the top of the file put the following two lines and it should work.
import os
os.chdir(os.path.dirname(os.path.realpath(__file__)))
Long term this either needs to be added to everything in PsychoPy that references a file in a local folder, or something about the way PsychoPy runs scripts needs to change.