fix: Trigger campaigns only during business hours (#3085)

Fixes #2433

app/views/api/v1/models/_campaign.json.jbuilder

@@ -17,5 +17,6 @@ if resource.campaign_type == 'one_off'
   json.audience resource.audience
 end
 json.trigger_rules resource.trigger_rules
+json.trigger_only_during_business_hours resource.trigger_only_during_business_hours
 json.created_at resource.created_at
 json.updated_at resource.updated_at