Add Belfast Ruby Luma Group (#1057)

Author: marcoroth

_data/meetup_groups.yml

@@ -91,6 +91,12 @@
   name: BelfastRuby
   service: meetupdotcom
 
+- id: belfastruby
+  name: Belfast Ruby
+  service: luma
+  ical_url: https://api.lu.ma/ics/get?entity=calendar&id=cal-6rPmMIYodqbr6WA
+  timezone: Europe/London
+
 - id: bmore-on-rails
   name: B'more on Rails
   service: meetupdotcom