bootstrap-navwalker will not load


Trying to implement wp-bootstrap-navwalker.php into my made from scratch template for wordpress.
The File for the class-wp-bootstrap-navwalker.php is located in the root directory of my theme.

functions.php

function register_navwalker() 

{ require_once get_template_directory() . ‘./class-wp-bootstrap-navwalker.php’;
} add_action( ‘after_setup_theme’, ‘register_navwalker’ );

cover.php With the code below within the <nav> and </nav> tags

  <?php     wp_nav_menu( array(         'theme_location'    => 'top-menu',         'depth'             => 2,         'container'         => 'div',         'container_class'   => 'collapse navbar-collapse',         'container_id'      => 'bs-example-navbar-collapse-1',         'menu_class'        => 'nav navbar-nav',         'fallback_cb'       => 'WP_Bootstrap_Navwalker::fallback',         'walker'            => new WP_Bootstrap_Navwalker(),     ) );     ?> 

When I save changes and reload my website, I get get the wp-bootstrap-navwalker page from github.

any help is much appreciated.