message: update webex changelog
diff: # 1.0.8
  * Update dependencies to Botkit 4.9, Bot Framework 4.9
  +* New: Add abilbity to start conversations or reply in a thread. Thanks to [@billyzoellers](https://github.com/billyzoellers) for the [pull request](https://github.com/howdyai/botkit/pull/1942)
  # 1.0.6
  