[FIX] account_set: Wrong recomputation of the depreciation lines

When a asset is confirmed, it's not allowed to link it to an invoice.
Side effect, it recomputed the depreciation lines of the confirmed asset.

opw:1961468

closes odoo/odoo#32388

Signed-off-by: Simon Goffin (sig) <sig@openerp.com>

addons/account_asset/views/account_asset_views.xml

@@ -133,7 +133,7 @@
                             <field name="salvage_value" widget="monetary" options="{'currency_field': 'currency_id'}" attrs="{'invisible': [('type','=','sale')]}"/>
                             <field name="value_residual" widget="monetary" options="{'currency_field': 'currency_id'}"/>
                             <field name="partner_id" string="Vendor" domain="[('supplier', '=', True)]"/>
-                            <field name="invoice_id" string="Invoice" options="{'no_create': True}"/>
+                            <field name="invoice_id" string="Invoice" attrs="{'readonly': [('state', '!=', 'draft')]}" options="{'no_create': True}"/>
                         </group>
                     </group>
                     <notebook colspan="4">