Remove extra slash from logo url

I put in a github pull request, then realized the version there is pretty old. BUT the fix is still needed in the latest wp-casify version.
In admin/admin-menu.php::wp_cassify_add_metabox_plugin_brand()
remove the slash at the start of the logo path so it looks like:
<div class="wp_cassify_brand"><img src="<?php echo $this->wp_cassify_plugin_directory . 'images/wp-cassify-logo.png'; ?>" /></div>

Because:
$this->wp_cassify_plugin_directory (derived from plugin_dir_url()) already includes the trailing slash

The page I need help with: [log in to see the link]