Prefect Slack Integration

The `prefect-slack` library provides official integrations for connecting Prefect 2.x workflows with Slack. It enables sending notifications and messages to Slack channels using webhooks or bot tokens, typically via Prefect Blocks. The current stable version is `0.3.1`, and it's part of the PrefectHQ monorepo, with releases often following the Prefect core library's major versions, though `prefect-slack` `0.3.1` is specifically for Prefect `2.x`.