remove useless group category

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@3614 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Form/PropertySheet/AccountingPreferences.py

@@ -59,5 +59,5 @@ class AccountingPreferences :
       'mode'        : 'w'},
   )
   
-  _categories = ('gap', 'group')
+  _categories = ('gap', )