perf(converterfactory.php): include '.art' TLD in pattern matching fo…

…r transitional processing

src/IDNA/Factory/ConverterFactory.php

@@ -142,6 +142,6 @@ public static function transitionalProcessing($keyword, $options = [])
             return $options["transitionalProcessing"];
         }
 
-        return mb_ereg("\./(be|ca|de|fr|pm|re|swiss|tf|wf|yt)\.?$/i", $options["domain"] ?? $keyword) !== false;
+        return mb_ereg("\./(art|be|ca|de|fr|pm|re|swiss|tf|wf|yt)\.?$/i", $options["domain"] ?? $keyword) !== false;
     }
 }