ANN: PyQt5 v5.15.8 and PyQt6 v6.4.1 Released

[Phil Thompson]

PyQt5 v5.15.8 and PyQt6 v6.4.1 have been released. These are minor 
functional releases.

Added to PyQt5...

- the missing QLocale.Language.NigerianPidgin member (Qt v5.15.2 and 
later)
- the missing QOperatingSystemVersion.MacOSBigSure attribute (Qt v5.15.1 
and later)
- the missing QThreadPool.contains() method (Qt v5.15.1 and later)
- the missing QBluetoothDeviceDiscoveryAgent.DiscoveryMethod members.

Added to PyQt6...

- allocationLimit() and setAllocationLimit() to QImageReader
- toHBITMAP(), fromHBITMAP(), toHICON() and fromHICON() to QImage on 
Windows.

PyQt3D v5.15.6 has also been released. This should build against Qt 
v5.15.8 and later.

Phil