hmPy requires 'PyQt5===5.9' according to setup.py:

    install_requires=[
        'PyQt5===5.9',
        'PyQtChart===5.9'
    ]

However, PyQt5 hasn't had 5.9 available for a long while. I think 5.14 is the earliest you can get nowadays and 5.15 has been out for a while as well. Is there anything in the repo that would break on a newer version? A manual setup with some hijacks is required now and that's sub-optimal at best.