payment_mean: add missing portal type in module listbox

Having a portal type is required to use the listbox as "Proxy Listbox ID" in a
relation field.

bt5/erp5_payment_mean/SkinTemplateItem/portal_skins/erp5_payment_mean/PaymentTransactionGroupModule_viewPaymentTransactionGroupList/listbox.xml

@@ -14,6 +14,7 @@
                 <string>columns</string>
                 <string>domain_root_list</string>
                 <string>domain_tree</string>
+                <string>portal_types</string>
                 <string>selection_name</string>
                 <string>title</string>
               </list>
@@ -201,6 +202,17 @@
                     <key> <string>form_id</string> </key>
                     <value> <string>Base_viewFieldLibrary</string> </value>
                 </item>
+                <item>
+                    <key> <string>portal_types</string> </key>
+                    <value>
+                      <list>
+                        <tuple>
+                          <string>Payment Transaction Group</string>
+                          <string>Payment Transaction Group</string>
+                        </tuple>
+                      </list>
+                    </value>
+                </item>
                 <item>
                     <key> <string>selection_name</string> </key>
                     <value> <string>payment_transaction_group_module_selection</string> </value>