Can't install dependencies: mismatch versions of PyQt5

[mergepony]

Hi. Faced with problem:

1. Cloned repo
2. Passed to folder
3. ran command pip3 install -r requirements.txt
4. Got following error

ERROR: Could not find a version that satisfies the requirement PyQt5==5.13.0 (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)
ERROR: No matching distribution found for PyQt5==5.13.

MacOS Big Sure 11.6
Pip: first try at 20.2.3, second try at 21.3