pip(deps): Bump slack-sdk from 3.27.2 to 3.28.0 in /scripts/pagerdu…

…ty/rota-to-slack (#4511)

 pip(deps): Bump slack-sdk

Bumps [slack-sdk](https://github.com/slackapi/python-slack-sdk) from 3.27.2 to 3.28.0.
- [Release notes](https://github.com/slackapi/python-slack-sdk/releases)
- [Changelog](https://github.com/slackapi/python-slack-sdk/blob/main/docs-v2/changelog.html)
- [Commits](slackapi/python-slack-sdk@v3.27.2...v3.28.0)

---
updated-dependencies:
- dependency-name: slack-sdk
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

scripts/pagerduty/rota-to-slack/requirements.txt

@@ -1,2 +1,2 @@
 pdpyras==5.2.0
-slack-sdk==3.27.2
+slack-sdk==3.28.0