PyQt6: QPropertyAnimation.setEasingCurve raises a SystemError

[Ales Erjavec]

Hi,

Calling QPropertyAnimation.setEasingCurve with a QEasingCurve.Type
raises a SystemError:

```
from PyQt6.QtCore import QPropertyAnimation, QEasingCurve

anim = QPropertyAnimation()
anim.setEasingCurve(QEasingCurve.Type.OutQuad)
```

According to https://www.riverbankcomputing.com/static/Docs/PyQt6/api/qtcore/qvariantanimation.html#setEasingCurve
this should work although Qt6 does not have this overload (was this
generated based on implicit QEasingCurve constructor?)

Windows 10
Python 3.8.8
PyQt6 6.1.0.dev2104191430

Best wishes
Aleš Erjavec