Updated to use PyQt6 instead of PyQt5

[monkeyclass]

As PyQt5 is not compatible with M1 Macs, this PR changes to use PyQt6.

At the moment I've gotten as far as to load the the screen from the Remarkable, but something fails then.

Most of the changes are related to qt6 has changed references to most functions, with intermediate functions.

This fixes #119

[bordaigorl]

Wow this is amazing, thanks so much for the effort!
I'll try to have a look soon and see if I can help.

[bordaigorl]

A quick test works on my machine.
Many interactions crash because they still use the old object hierarchy.
Is there no tool around that can trigger warnings statically for breaking changes between qt5 and qt6?

[monkeyclass]

A quick test works on my machine.
Many interactions crash because they still use the old object hierarchy.
Is there no tool around that can trigger warnings statically for breaking changes between qt5 and qt6?

I’m not sure, would be great. Completely agree that it’s a bit slow process. I will get around to looking at it again next week, and hopefully get the rest replaced.