Update RubyConf TH 2026 name and add 2023 URL

Author: marcoroth

_data/conferences.yml

@@ -2430,7 +2430,7 @@
   location: Bangkok, Thailand
   start_date: 2023-10-06
   end_date: 2023-10-07
-  url: https://rubyconfth.com/
+  url: https://rubyconfth.com/past/2023/
   twitter: rubyconfth
   mastodon: https://ruby.social/@rubyconfth
   cfp_open_date: 2023-04-03
@@ -3056,11 +3056,11 @@
   mastodon: https://ruby.social/@rockymtnruby
   announced_on: 2024-10-08
 
-- name: RubyConf Thailand
+- name: RubyConf TH 2026
   location: Bangkok, Thailand
   start_date: 2026-01-31
   end_date: 2026-02-01
   date_precision: year
   url: https://rubyconfth.com
   twitter: rubyconfth
-  announced_on: 2025-02-28
+  announced_on: 2025-02-28