Annoying PHP has no concept of deprecation for these functions. You have several rand variants and only one or two are worth your time.
At least they put it in their reference manual…
Just use openssl_random_pseudo_bytes().
Or better: http://php.net/manual/en/function.random-bytes.php in PHP >= 7 and this wrapper for PHP < 7: https://packagist.org/packages/paragonie/random_compat