[FIX] hr_expense: add missing state field used in modifiers fields

The domain is add in the view from the python field description.

Issue:
In expense go in "to Approve" > "Expense Reports to Approve"
Create a new expense sheet by clicking create
Add an expense to the sheet
Click create in the bottom left

result: Uncaught Error: Unknown field state in domain

addons/hr_expense/views/hr_expense_views.xml

@@ -41,6 +41,7 @@
             <field eval="35" name="priority"/>
             <field name="arch" type="xml">
                 <form string="Expenses" class="o_expense_form">
+                <field name="state" invisible="True"/>
                 <sheet>
                     <div class="oe_title">
                         <label for="name"/>