[PyQt] PYQt defaults to fonts looking bold on macOS but C++ Qt does not

[Barry Scott]

Compare the windows snapshots taken for a PyQt5 app and a C++ Qt5 app
that use a QLabel control.

http://www.barrys-emacs.org/export/Qt5.png

http://www.barrys-emacs.org/export/PyQt5.png

You can see that the text in PyQt5 looks like it is bold compared to the
Qt5 version.

On Fedora I see that same text for Qt5 and PyQT5.

Please fix this problem in PyQt5.

The source code I used is in:

http://barrys-emacs.org/export/font-example.tar.gz

Note: This bug affects all text, list, tables, line edit everything.

Barry