[IMP] website: remove navbar extra padding

In the mobile view, the header has extra padding, for this
reason it is not perfectly aligned with the content of the page.

addons/website/views/website_templates.xml

@@ -318,7 +318,7 @@
 <!-- TODO adapt in master: remove o_main_nav id -->
 <template id="template_header_mobile" name="Template Header Mobile">
     <t t-call="website.navbar">
-        <t t-set="_navbar_classes" t-valuef="o_header_mobile d-block d-lg-none shadow-sm"/>
+        <t t-set="_navbar_classes" t-valuef="o_header_mobile d-block d-lg-none shadow-sm px-0"/>
         <t t-set="_navbar_expand_class" t-valuef="None"/>
         <t t-set="_navbar_name" t-valuef="Mobile"/>