[FIX] stock_account: Force accounting date on validated inventory adjustment

When the inventory adjustement has been validated, changing accounting_date has no
impact on the stock moves created by the inventory adjustement.
This behavior cannot be changed in stable version.

opw:1817813

addons/stock_account/views/stock_account_views.xml

@@ -8,7 +8,7 @@
             <field name="inherit_id" ref="stock.view_inventory_form"/>
             <field name="arch" type="xml">
                 <xpath expr="//field[@name='date']" position="after">
-                    <field name="accounting_date"/>
+                    <field name="accounting_date" attrs="{'readonly':[('state','!=', 'draft')]}"/>
                 </xpath>
             </field>
         </record>