orderby taxonomies portfolio categories

Hello!
I want to order by slug my portfolio categories.
I already checked out here:

https://codex.www.ads-software.com/Function_Reference/get_terms

https://codex.www.ads-software.com/Function_Reference/get_categories

This is my code on portfolio-page.php:

<?php
                        $taxonomies = get_terms('project-type', 'orderby=count&hide_empty=0');
                        foreach ($taxonomies as $tax) {
                            echo '<li><a href="#filter" data-option-value=".' . $tax->slug . '">' . $tax->name . '</a></li>';
                        }
                        ?>

I don’t manage to make it work and all the plugins I find have not been tested yet on my wp version.

Any idea of how to add ‘orderby’ => ‘slug’ on the code above?
Thanks in advance!