Remove outdated config to generate sitemap

Author: yasulab

config/sitemap.rb

@@ -1,8 +1,7 @@
 # Set the host name for URL creation
 SitemapGenerator::Sitemap.default_host = "https://coderdojo.jp"
 
-# Configure search engines to ping (exclude Google as it's deprecated)
-SitemapGenerator::Sitemap.ping_search_engines = true
+# Configure search engines to ping
 SitemapGenerator::Sitemap.search_engines = {
   'bing' => 'http://www.bing.com/ping?siteMap=%s',
   # Google を非推奨になったため除外: https://developers.google.com/search/blog/2023/06/sitemaps-lastmod-ping