Fix the name of Matsue RubyKaigi (ruby-conferences#714)

Sorry it was my mistake.

Author: okuramasafumi

_data/conferences.yml

@@ -2716,7 +2716,7 @@
   cfp_link: https://sessionize.com/rails-world/
   announced_on: 2023-11-30
 
-- name: Matsue RubyistKaigi 11
+- name: Matsue RubyKaigi 11
   location: Matsue, Japan
   start_date: 2024-10-05
   end_date: 2024-10-05