Issue in /src/pages/guides/creating-python-plugin.md

I was going over the "Creating a Python plugin" tutorial, and had issues running the custom_import.py plugin code. It seems that PySide 2 is not supported in the most recent version of Substance Painter.

Is the following more appropriate? While I still had errors after making this change, at least it loaded the plugin.

from PySide6 import QtWidgets
from PySide6.QtGui import QAction

Start with src/pages/guides/creating-python-plugin.md and review the custom_import.py example alongside the reported PySide2 and PySide6 imports. Confirm which import form is supported in the current Substance Painter version, then update the tutorial so the example loads without the reported import issue.

Written by the indexing model from the issue text.