Apply dualmethod decorator to post method of account move

Since efdb98eb55e5 the original method is a dualmethod.

Closes #12682

modules/account_statement/account.py

@@ -1,7 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 from trytond.i18n import gettext
-from trytond.model import ModelView
+from trytond.model import ModelView, dualmethod
 from trytond.modules.account.exceptions import PostError
 from trytond.pool import Pool, PoolMeta
 
@@ -22,7 +22,7 @@ class Move(metaclass=PoolMeta):
     def _get_origin(cls):
         return super(Move, cls)._get_origin() + ['account.statement']
 
-    @classmethod
+    @dualmethod
     @ModelView.button
     def post(cls, moves):
         pool = Pool()

modules/account_tax_cash/account.py

@@ -6,7 +6,7 @@ from itertools import groupby
 from sql import Literal, Null
 
 from trytond.i18n import gettext
-from trytond.model import ModelSQL, ModelView, Workflow, fields
+from trytond.model import ModelSQL, ModelView, Workflow, dualmethod, fields
 from trytond.pool import Pool, PoolMeta
 from trytond.pyson import Eval
 from trytond.tools import sortable_values
@@ -192,7 +192,7 @@ class TaxLine(metaclass=PoolMeta):
 class Move(metaclass=PoolMeta):
     __name__ = 'account.move'
 
-    @classmethod
+    @dualmethod
     @ModelView.button
     def post(cls, moves):
         pool = Pool()

modules/analytic_account/line.py

@@ -6,7 +6,7 @@ from itertools import groupby
 
 from sql import Literal
 
-from trytond.model import Check, Index, ModelSQL, ModelView, fields
+from trytond.model import Check, Index, ModelSQL, ModelView, dualmethod, fields
 from trytond.modules.currency.fields import Monetary
 from trytond.pool import Pool, PoolMeta
 from trytond.pyson import Eval, PYSONEncoder
@@ -140,7 +140,7 @@ class Line(ModelSQL, ModelView):
 class Move(metaclass=PoolMeta):
     __name__ = 'account.move'
 
-    @classmethod
+    @dualmethod
     @ModelView.button
     def post(cls, moves):
         pool = Pool()