App: fixes #10460: App::PropertyPythonObject is not saving data

Since Py3.11 the methods names __setstate__ and __getstate__ conflict with the method names added to the object class.
Thus rename them to 'loads' and 'dumps'

src/Mod/Part/JoinFeatures.py

@@ -142,10 +142,10 @@ class _ViewProviderPartJoinFeature:
     def unsetEdit(self, vobj, mode):
         return
 
-    def __getstate__(self):
+    def dumps(self):
         return None
 
-    def __setstate__(self, state):
+    def loads(self, state):
         return None
 
     def claimChildren(self):