PunyencodeAddressTest: add additional test case
PunyencodeAddressTest: add additional test case

... to ensure that the `PHPMailer::punyencodeAddress()` only acts on the domain.

jimjag/PHPMailer,jimjag/PHPMailer,nawawi/PHPMailer,PHPMailer/PHPMailer,nawawi/PHPMailer,PHPMailer/PHPMailer