views-page-title.php

<?php

/**
 * Implements hook_views_post_render().
 */
function MODULE_NAME_views_post_render($view) {
  if ($view->id() !== 'VIEW_ID' && $view->getDisplay()->getPluginId() !== 'page') {
    return;
  }

  $request = \Drupal::request();

  if ($route = $request->attributes->get(\Symfony\Cmf\Component\Routing\RouteObjectInterface::ROUTE_OBJECT)) {
    $new_title = $view->getTitle();
    $route->setDefault('_title', $new_title);
  }
}