Fetch posts from category in custom page template

by

You can use WP_Query instead the get_posts() function:

  $args = array( 'numberposts' => 20, 'category_name' => 'sell-items' );  
  $wp_query = new WP_Query($args);

if ($wp_query->have_posts()) : while($wp_query->have_posts()) : $wp_query->the_post();

echo '<li><a href="'.get_the_permalink().'">'.get_the_title().'</a></li>';
    endwhile;
  endif;