[Qt6] Update sample macros for migration to Qt6

[Kazzz-S]

Some sample macros need to be updated to address errors observed when migrating to Qt6, such as:

The above images were captured on:

They should be modified like: (also refer to #1676)

1. pya.FormBuilder() ---> pya.QUiLoader()
2. pya.QFont.Bold ---> int(pya.QFont_Weight().Bold)

Regards,
Kazzz-S