Update res_partner_view.xml

No need to write on customer_rank and supplier_rank here.
This creates a conflict with partner_manual_rank module.

contract/views/res_partner_view.xml

@@ -8,7 +8,7 @@
         <field name="groups_id" eval="[(4, ref('account.group_account_invoice'))]" />
         <field type="xml" name="arch">
             <xpath expr="//div[@name='button_box']" position="inside">
-                <field name="customer_rank" invisible="1" />
+                <field name="customer_rank" invisible="1" readonly="1"/>
                 <button
                     name="act_show_contract"
                     type="object"
@@ -24,7 +24,7 @@
                         string="Sale Contracts"
                     />
                 </button>
-                <field name="supplier_rank" invisible="1" />
+                <field name="supplier_rank" invisible="1" readonly="1"/>
                 <button
                     name="act_show_contract"
                     type="object"