Error installing on Mac: No matching distribution found for PyQt5==5.13.1

[toonst]

When installing inside virtual environment on Mac, I get the following error:

ERROR: Could not find a version that satisfies the requirement PyQt5==5.13.1 (from versions: 5.14.0, 5.14.1, 5.14.2, 5.15.0, 5.15.1, 5.15.2, 5.15.3, 5.15.4, 5.15.5, 5.15.6, 5.15.7, 5.15.8, 5.15.9)
ERROR: No matching distribution found for PyQt5==5.13.1

Since some components require ALSA audio, maybe this package is not Mac compatible? Would be good to indicate this on the README if that is the case.