credential: fix "Update Credentials" condition

it should be displayed if user can add a credential update

bt5/erp5_credential/ActionTemplateItem/portal_types/portal_actions/update_credentials.xml

@@ -78,7 +78,7 @@
       <dictionary>
         <item>
             <key> <string>text</string> </key>
-            <value> <string>python: here.ERP5Site_getAuthenticatedMemberPersonValue() is not None</string> </value>
+            <value> <string>python: portal.Base_checkPermission(\'credential_update_module\', \'Add portal content\')</string> </value>
         </item>
       </dictionary>
     </pickle>