[FIX] lunch: removing kanban border-bottom

=== ISSUE ===

If you open the lunch module with the Kanban view activated, there is
a border at the bottom of the view, which was previously used to create
a separation between two elements of different colors.

Since Milk brings a fresh new design, this border was removed on other
kanbans but not this one which makes it not consistent.

=== AFTER ===

We remove that `border-bottom` class to make the view consistent with
other kanbans.

task-3328235
part of task-3326263

closes odoo/odoo#123946

X-original-commit: 4e4846ac9c78ce6775baebf1a073bdc67164b6bb
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/lunch/static/src/views/kanban.xml

@@ -4,7 +4,7 @@
         <div class="o_lunch_content d-flex flex-column h-100">
             <LunchDashboard openOrderLine.bind="openOrderLine"/>
 
-            <div class="overflow-auto border-top border-bottom">
+            <div class="overflow-auto border-top">
                 <t t-call="web.KanbanRenderer"/>
             </div>
         </div>