[REF] *: BS4, adapt col-related classes

See https://github.com/odoo/odoo/commit/ed1b18f10348244ce26b8b27edbd59d91cee7772

static/src/xml/website_form_editor.xml

@@ -29,12 +29,12 @@
     <!-- Generic Field Layout -->
     <t t-name="website_form_editor.field">
         <div t-att-class="'form-group form-field' + (field.custom ? ' o_website_form_custom' : '') + (field.required ? ' o_website_form_required' : '')">
-            <div class="col-md-3 col-sm-4 text-right-not-xs">
+            <div class="col-lg-3 col-md-4 text-right-not-xs">
                 <label class="control-label" t-att-for="field.name">
                     <t t-esc="field.string"/>
                 </label>
             </div>
-            <div class="col-md-7 col-sm-8">
+            <div class="col-lg-7 col-md-8">
                 <t t-raw="0"/>
             </div>
         </div>

views/snippets.xml

@@ -4,7 +4,7 @@
         <template id="s_website_form" name="Form Builder">
             <form action="/website_form/" method="post" class="s_website_form form-horizontal container-fluid mt32" enctype="multipart/form-data">
                 <div class="form-group">
-                    <div class="col-md-offset-3 col-sm-offset-4 col-sm-8 col-md-7">
+                    <div class="offset-lg-3 offset-md-4 col-md-8 col-lg-7">
                         <button class="btn btn-primary btn-lg o_website_form_send">Send</button>
                         <span id="o_website_form_result"></span>
                     </div>