se adiciona atributo default a many2one y attribute

FossilOrigin-Name: 9ddb1d1b8bebef24da17cc47d8fc70392f6015bb61866f251992aea518ed3d0f

facho/model/fields/attribute.py

@@ -4,6 +4,7 @@ class Attribute(Field):
     def __init__(self, tag, default=None):
         self.tag = tag
         self.value = default
+        self.default = default
 
     def __get__(self, inst, cls):
         if inst is None: