title: Remove Woocommerce review tab if empty
body: <p>How can I hide the Review tab for products without reviews only? I've found this code:</p>
  
  <p><code>add_filter( 'woocommerce_product_tabs', 'delete_tab', 98 );
      function delete_tab( $tabs ) {
      unset($tabs['reviews']);
      return $tabs;
  }</code></p>
  
  <p>But it removes the Reviews everywhere, even in products that do have some reviews.</p>