# What this PR does
- update `slackclient` dependency to latest version. The version we were
using was 5 years old 😲
- first followed the v2 migration guide
[here](https://github.com/slackapi/python-slack-sdk/wiki/Migrating-to-2.x)
followed by the v3 migration guide
[here](https://slack.dev/python-slack-sdk/v3-migration/). The main
changes were:
- The PyPI project was renamed from `slackclient` to `slack_sdk`
- it is discouraged/harder to call `api_call` and encouraged to call the
helper methods (ex. `chat_postMessage`;
[note](https://github.com/slackapi/python-slack-sdk/wiki/Migrating-to-2.x#web-client-api-changes)
in migration guide docs)
- In 1.x, a failed api call would return the error payload to you and
have you handle the error. In 2.x, a failed api call will throw an
exception. To handle this in your code, you will have to wrap api calls
with a try except block. Since we overload `WebClient.api_call` this was
an easy change and only required a one line change
- remove `apps.slack.slack_client.slack_server.SlackClientServer` class.
The new version of `slack_sdk` handles the case that we needed to
overload for in the first place.
- merged `apps/slack/slack_client/slack_client.py` and
`apps/slack/slack_client/exceptions.py` into `apps/slack/client.py`
## Checklist
- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)
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