Segfault when using a QByteArray in place of a Python byte array (Limited API)

TLDR: feeding a `QByteArray` to `struct.unpack()` causes a segfault. To reproduce:

>>> import struct
>>> from PySide6.QtCore import QByteArray
>>> struct.unpack('<ii', b'\x19\x00\x00\x00\xc4\t\x00\x00')
(25, 2500)
>>> b = QByteArray(b'\x19\x00\x00\x00\xc4\t\x00\x00')
>>> struct.unpack('<ii', b)
Segmentation fault (core dumped)

The longer story:

A project previously used PyQt5 and is being migrated to PySide6. The code previously used to read data from `QTcpSocket.read()` and parse the bytes with `struct.unpack()`. After the upgrade, this crash emerged.

It's a pretty easy fix, the `QByteArray` can just be converted to a normal Python `bytes` object right after the `QTcpSocket.read()`.

I'm not sure exactly where the bug is... `struct.unpack()` should raise an exception if it gets a type it can't deal with. For example:

>>> import struct
>>> from PySide6.QtCore import QObject, QByteArray
>>> struct.unpack('<ii', QObject())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: a bytes-like object is required, not 'PySide6.QtCore.QObject'

So, maybe that's a Python `struct` problem? But then I wonder, if the Python `bytes` class is more or less equivalent to the `QByteArray` class, should `QIODevice.read()` return `bytes` instead of `QByteArray` in PySide? Does `QByteArray` not behave as a "bytes-like object" under all conditions? Not sure, but it's easy to reproduce. Let me know if anything else is needed.