[FIX] mrp: stock move not applied on kanban state change

In manufacturing orders, there is a kanban view.

The kanban items are drag & droppable from a column into another.
When moving an item into the "cancelled column", the stock move
is not applied.

Actually, you can't change the state of a MO by clicking on the state
in the status bar. So, the expected behavior is that you can't drag
and drop an item into another column.

According to this, I reproduced the same behavior than in V13.

Before this commit:

    - The kanban items can be drag and dropped from a column into
      another but there is no stock move

After this commit:

    - The kanban items cannot be drag and dropped like in V13.

OPW-2081255

closes odoo/odoo#38761

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/mrp/views/mrp_production_views.xml

@@ -179,7 +179,7 @@
                     <field name="product_qty"/>
                      <field name="product_uom_id" options="{'no_open':True,'no_create':True}"/>
                     <field name="date_planned_start"/>
-                    <field name="state"/>
+                    <field name="state" readonly="1"/>
                     <templates>
                         <t t-name="kanban-box">
                             <div t-attf-class="oe_kanban_card oe_kanban_global_click">