Update PyQt > 5.6

[tfoerst3r]

Request for an update of the project.

The last version on pypi.org for pyqt5 is 5.7.1

$>> pip install PyQt5==5.6
ERROR: Could not find a version that satisfies the requirement PyQt5==5.6 (from versions: 5.7.1, 5.8, 5.8.1.1, 5.8.2, 5.9, 5.9.1, 5.9.2, 5.10, 5.10.1, 5.11.2, 5.11.3, 5.12, 5.12.1, 5.12.2, 5.12.3, 5.13.0, 5.13.1, 5.13.2, 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)
ERROR: No matching distribution found for PyQt5==5.6

This makes it literally difficult to install without an old system installation or a not standard conda env with an old pyqt5 < 5.7.