Add Ruby Belgium Summer 2025 (ruby-conferences#1086)

Author: wJoenn

_data/meetups.yml

@@ -6541,6 +6541,13 @@
   end_time: 21:30:00 EDT
   url: https://www.meetup.com/charlotte-rb/events/mhkrrtyhckbcb
 
+- name: Ruby Belgium Meetup Summer 2025
+  location: Brussels, Belgium
+  date: 2025-07-01
+  start_time: 18:00:00 CEST
+  end_time: 22:00:00 CEST
+  url: https://lu.ma/g8adodhj
+
 - name: RubyJax - Open Hax July 2025
   location: Jacksonville, FL
   date: 2025-07-01