Update RubyWorld 2025 URL

Author: marcoroth

_data/conferences.yml

@@ -3139,8 +3139,7 @@
   location: Matsue, Japan
   start_date: 2025-11-06
   end_date: 2025-11-07
-  # TODO: url is an annoucement page, not an official page for 2025
-  url: https://2024.rubyworld-conf.org/ja/news/2025/01/rwc2025/
+  url: https://2025.rubyworld-conf.org/en/
   twitter: rubyworldconf
   announced_on: 2025-01-10