`QtTextToSpeech` is a part of `PySide6`, but is not loadable through `QtPy`

[StSav012]

QtTextToSpeech.py disallows loading QtTextToSpeech, although it's present in PySide6 since version 6.5 at least.

I don't have time to test all available versions of PySide6 and PyQt6. As soon as I find it, I'll update the issue unless someone resolves it.