FIX: Do not downcase group name in notification payload

Followup to 3d39b4bb

app/services/post_alerter.rb

@@ -223,7 +223,7 @@ class PostAlerter
     topic.allowed_groups.map do |g|
       {
         group_id: g.id,
-        group_name: g.name.downcase,
+        group_name: g.name,
         inbox_count: DB.query_single(sql, group_id: g.id).first.to_i
       }
     end