Fix navbar dividers: border-start on the link itself instead of a standalone vr div

The vr utility needs stretch alignment from its flex parent to size
correctly -- inside a plain nav-item li it collapsed/misaligned instead
of showing as a clean vertical rule.

views/_navbar.erb

@@ -9,9 +9,8 @@
         <li class="nav-item">
           <a class="nav-link <%= 'active' if request.path == '/' %>" href="/">Home</a>
         </li>
-        <li class="nav-item"><div class="vr mx-2 my-2"></div></li>
         <li class="nav-item">
-          <a class="nav-link <%= 'active' if request.path.start_with?('/brother') %>" href="/brother">Brother</a>
+          <a class="nav-link border-start ps-3 <%= 'active' if request.path.start_with?('/brother') %>" href="/brother">Brother</a>
         </li>
         <li class="nav-item">
           <a class="nav-link <%= 'active' if request.path == '/upload' %>" href="/upload">Shipping labels</a>
@@ -19,9 +18,8 @@
         <li class="nav-item">
           <a class="nav-link <%= 'active' if request.path == '/epson' %>" href="/epson">Receipts</a>
         </li>
-        <li class="nav-item"><div class="vr mx-2 my-2"></div></li>
         <li class="nav-item">
-          <a class="nav-link <%= 'active' if request.path.start_with?('/labels') %>" href="/labels">Labels</a>
+          <a class="nav-link border-start ps-3 <%= 'active' if request.path.start_with?('/labels') %>" href="/labels">Labels</a>
         </li>
       </ul>
       <% if request.path.start_with?('/brother') %>