Current category link filter

Internally wp_list_categories() uses get_term_link() for the URL of the terms. That function can be filtered using the term_link filter, so you could filter any links to the current term and replace them with links to the post type archive:

function wpse_307202_term_link( $termlink, $term, $taxonomy ) {
    if ( is_tax( 'cat_projet' ) ) {
        if ( get_queried_object_id() === $term->term_id ) {
            $termlink = get_post_type_archive_link( 'post_type_name' );
        }
    }

    return $termlink;
}
add_filter( 'term_link', 'wpse_307202_term_link', 10, 3 );