Slack Client (Legacy Package)

The `slackclient` library is the legacy Python client for the Slack Web API and RTM API. Version 2.9.4 is the last release, and the project is officially deprecated. Users are strongly advised to migrate to the `slack-sdk` package, which is the actively maintained and officially supported Slack Python SDK. While `slackclient` v2.x shared similar import paths with `slack-sdk` (e.g., `from slack import WebClient`), the `slack-sdk` project has continued development and introduced new features and improvements.