Issue-257: Fix PHP 7.3 compatibility issues. (#264)

Author: kish0808

src/Validation/DNSCheckValidation.php

@@ -97,10 +97,7 @@ public function getWarnings()
      */
     protected function checkDns($host)
     {
-        $variant = INTL_IDNA_VARIANT_2003;
-        if (defined('INTL_IDNA_VARIANT_UTS46')) {
-            $variant = INTL_IDNA_VARIANT_UTS46;
-        }
+        $variant = INTL_IDNA_VARIANT_UTS46;
 
         $host = rtrim(idn_to_ascii($host, IDNA_DEFAULT, $variant), '.') . '.';