QWheelEvent delta() not available

[callistopili]

at line 61 the library fails due to the missing member 'delta'
when using the ProbertyBin widget

the fix for the QT member is to use "event.angleDelta().y()" instead of "delta()"

NodeGraphQt/NodeGraphQt/custom_widgets/properties_bin.py

Line 61 in 34c9356

delta = event.delta() * 0.2