Support running PySide on Python 3.12

Support running PySide on Python 3.12

Builtin types no longer have tp_dict set. We need to
use PyType_GetDict, instead. This works without Limited API
at the moment.

With some great cheating, this works with Limited API, too.
We emulate PyType_GetDict by tp_dict if that is not 0.
Otherwise we create an empty dict.

Some small changes to Exception handling and longer
warm-up in leaking tests were found, too.

Pick-to: 6.6 6.5 6.2
Task-number: PYSIDE-2230
Change-Id: I8a56de6208ec00979255b39b5784dfc9b4b92def
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
(cherry picked from commit 441ffbd4fc622e67acd81e9c1c6d3a0b0fbcacf0)

Gbp-Pq: Name Support-running-PySide-on-Python-3.12.patch