"Donate Now" links has wrong semantics and no focus styling (Accessibility)

This is just noting two accessibility problems with the "Donate Now" link at the top and footer of the page.

The HTML context is

<nav>
  ...
  <h4 class="pl-2 pr-2">
    <a href="https://donate.torproject.org" title="Donate"><span class="badge badge-warning p-2">Donate Now</span></a>
  </h4>
  ...
</nav>

The wrapped <h4> shouldn't be there and makes for confusing screen reader output.

The other issue is that the "Donate Now" link has no :focus-visible or :focus styling for visual feedback to keyboard users.