[BS5] change bootstrap general

data/web/templates/admin/tab-sys-mails.twig

@@ -53,14 +53,14 @@
           </div>
         </div>
         <div class="form-group">
-          <div class="col-sm-offset-2 col-sm-10">
+          <div class="offset-sm-2 col-sm-10">
             <label>
               <input type="checkbox" id="mass_disarm"> {{ lang.admin.activate_send }}
             </label>
           </div>
         </div>
         <div class="form-group">
-          <div class="col-sm-offset-2 col-sm-10">
+          <div class="offset-sm-2 col-sm-10">
             <button class="btn btn-sm d-block d-sm-inline btn-success" type="submit" id="mass_send" name="mass_send" disabled><i class="bi bi-envelope-fill"></i> {{ lang.admin.send }}</button>
           </div>
         </div>