Upgrade Jetty

[kurtostfeld]

This slack sdk uses Jetty 9.x which is wildly out of date and EOL. Jetty 12.1 is the current version; that would be best.

[hello-ashleyintech]

Hi, @kurtostfeld! Thank you so much for raising this to our attention. 😄 I will let our internal dev expert for the Java SDK know, but I have also tagged this as a good first issue if you or any other community member would like to give upgrading this a shot!

[github-actions]

👋 It looks like this issue has been open for 30 days with no activity. We'll mark this as stale for now, and wait 10 days for an update or for further comment before closing this issue out. If you think this issue needs to be prioritized, please comment to get the thread going again! Maintainers also review issues marked as stale on a regular basis and comment or adjust status if the issue needs to be reprioritized.