[Polylang] add changes to language code in alternate links

//Change polylang code alternate 

add_filter('pll_rel_hreflang_attributes', 'filter_pll_rel_hreflang_attributes', 10, 1);

function filter_pll_rel_hreflang_attributes($hreflangs)
{
  foreach ($hreflangs as $lang => $url) {

    if ($lang == 'uk') {
      $hreflangs['uk-UA'] = $hreflangs['uk'];
      unset($hreflangs['uk']);
    } else if ($lang == 'ru') {
      $hreflangs['ru-UA'] = $hreflangs['ru'];
      unset($hreflangs['ru']);
    }
  }

  return $hreflangs;
};