Update changelog for impending release of v3.0.9 (#105)

## Description of the change

> Write a brief description of your change here. 

## Checklist

- [ ] I performed a self-review of my code
- [ ] I manually tested my code change (please list details in description)
- [ ] I added unit tests 
- [ ] I updated the changelog
- [ ] I updated the public facing docs

CHANGELOG.md

@@ -1,4 +1,9 @@
 # Changelog
+
+## v3.0.9
+- Add risk sensitivity and overrides
+- Add default empty arrays for a few fields (visibility_group_ids, message_channel_ids, member_oncall_schedule_ids, on_call_schedule_ids)
+
 ## v3.0.8
 - Fix state upgrader when going from v2.x to latest version.