Why wp_kses() not working for rel, target of link in Wordpress

I am using below code for wp_kses(). But it's ignoring rel target in the result. I want to show rel="nofolow" target="_blank" in my result (link).

$link = "Here is my link: a href="my-link" rel="nofollow" target="_blank"Link Text/a" 

$allowed_tags= array(
                        'br' = array(),
                        'p' = array(),
                        'a'  = array(
                                'href'     = true,
                                'rel'      = true,
                                'target'   = true,                             
                            ),
                );


$result = wp_kses( $link, $allowed_tags );

Output result: Here is my link: a href="my-link"Link Text/a

Expected result: Here is my link: a href="my-link" rel="nofollow" target="_blank"Link Text/a