Addon Manager: Qt6 migration part 1, use PySide

Migrate all uses of "import PySide 2" to use "import PySide" so that the
FreeCAD-provided wrappers can switch between Qt versions.

src/Mod/AddonManager/addonmanager_devmode_person_editor.py

@@ -25,7 +25,7 @@
 import os
 from typing import Tuple  # Needed until Py 3.9, when tuple supports this directly
 
-from PySide2.QtWidgets import QDialog
+from PySide.QtWidgets import QDialog
 
 import FreeCAD
 import FreeCADGui