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_licenses_table.py

@@ -24,8 +24,8 @@
 
 import os
 
-from PySide2.QtWidgets import QTableWidgetItem
-from PySide2.QtGui import QIcon
+from PySide.QtWidgets import QTableWidgetItem
+from PySide.QtGui import QIcon
 
 import FreeCAD
 import FreeCADGui