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/Assembly/JointObject.py

@@ -443,13 +443,13 @@ class ViewProviderJoint:
 
         return ":/icons/Assembly_CreateJoint.svg"
 
-    def __getstate__(self):
+    def dumps(self):
         """When saving the document this object gets stored using Python's json module.\
                 Since we have some un-serializable parts here -- the Coin stuff -- we must define this method\
                 to return a tuple of all serializable objects or None."""
         return None
 
-    def __setstate__(self, state):
+    def loads(self, state):
         """When restoring the serialized object from document we have the chance to set some internals here.\
                 Since no data were serialized nothing needs to be done here."""
         return None