Use PySide6 instead of PySide2 to get QtDesigner

[kotopesutility]

There is no QtDesigner in PySide2

>>> PySide2.__version__
'5.13.2'
>>> from PySide2 import QtDesigner
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'QtDesigner' from 'PySide2' (/tmp/.private/kotopesutility/VENV/lib64/python3/site-packages/PySide2/__init__.py)