Bump @slack/client from 4.12.0 to 5.0.2

Bumps [@slack/client](https://github.com/slackapi/node-slack-sdk) from 4.12.0 to 5.0.2.
- [Release notes](https://github.com/slackapi/node-slack-sdk/releases)
- [Commits](https://github.com/slackapi/node-slack-sdk/compare/v4.12.0...@slack/client@5.0.2)

---
updated-dependencies:
- dependency-name: "@slack/client"
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Author: dependabot[bot]