Try this:

$the_cat = \'latest\';
$term_args = array(\'orderby\' => \'term_id\', \'order\' => \'ASC\', \'fields\' => array(\'term_id\', \'slug\'));
$terms = wp_get_post_terms( $post->ID, \'category\', $term_args );
foreach($terms as $term){
    if($term->slug !== $the_cat){
        $terms_to_exclude .= $term->term_id.\',\';
    }
}
$next_post = get_next_post($in_same_term = true, $excluded_terms = $terms_to_exclude, $taxonomy = \'category\');