I already tried in several ways to remove the last slash of the url that I created with add_rewrite_rule.

below is the implementation of my code

function master_load_ads_txt_template_include($template) {
  $is_load_ads_txt = (bool)get_query_var('ads-txt');
  if( $is_load_ads_txt ) {
    $template = get_template_part("template-parts/ads-txt");
  }

  return $template;
}
add_action( 'template_include', 'master_load_ads_txt_template_include' );

function master_load_ads_txt_rewrite() {
  add_rewrite_rule('ads.txt', 'index.php?ads-txt=true', 'top');
  add_rewrite_rule('^ads.txt/', 'ads.txt', 'top');
}
add_action('init', 'master_load_ads_txt_rewrite');

function master_load_ads_txt_query_vars( $query_vars ) {
  $query_vars[] = 'ads-txt';
  return $query_vars;
}
add_filter( 'query_vars', 'master_load_ads_txt_query_vars');

the code is working but does not remove the slash at the end of the url