ANN: PyQt v5.15.4 and v6.0.3 Released

[Phil Thompson]

PyQt v5.15.4 and v6.0.3 have been released - along with corresponding 
versions of everything else.

The main purpose of these releases is to work around the pip issues when 
updating to v5.15.3 and v6.0.2.

If you did update to those versions, and now update to the latest 
versions you will have an unused Qt installation installed. To remove 
these run...

pip uninstall PyQt5-Qt
pip uninstall PyQt3D-Qt
pip uninstall PyQt6-Qt

...etc, etc.

Phil