Jetty upgrades to v11

[seratch]

In the next major version, we may want to upgrade the major version of Jetty HTTP server from v9 to v11. This upgrades affects only bolt-jetty module users. That being said, as long as the existing apps do not use any Jetty specific features, the upgrades won't bring any breaking changes.

Category (place an x in each of the [ ])

• bolt (Bolt for Java)
• bolt-{sub modules} (Bolt for Java - optional modules)
• slack-api-client (Slack API Clients)
• slack-api-model (Slack API Data Models)
• slack-api-*-kotlin-extension (Kotlin Extensions for Slack API Clients)
• slack-app-backend (The primitive layer of Bolt for Java)

Requirements

Please make sure if this topic is specific to this SDK. For general questions/issues about Slack API platform or its server-side, could you submit questions at https://my.slack.com/help/requests/new instead. 🙇

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[seratch]

We were going to upgrade Jetty to v11 in the next major version but after the discussion at #919 (comment), we decided to add bolt-jakarta-jetty as a new module. Since v1.18, users can go with the new module if they want to switch to Jakarta EE Servlets.