chore(deps): bump slackapi/slack-github-action in the actions group (#5930)

Bumps the actions group with 1 update: [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action).

Updates `slackapi/slack-github-action` from 2.1.0 to 2.1.1
- [Release notes](https://github.com/slackapi/slack-github-action/releases)
- [Commits](https://github.com/slackapi/slack-github-action/compare/b0fa283ad8fea605de13dc3f449259339835fc52...91efab103c0de0a537f72a35f6b8cda0ee76bf0a)

---
updated-dependencies:
- dependency-name: slackapi/slack-github-action
  dependency-version: 2.1.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
...

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

.github/workflows/test-cli-ui_oss.yml

@@ -112,7 +112,7 @@ jobs:
           make -C internal/tests/cli test-vault-down
       - name: Send Slack message
         if: ${{ failure() }}
-        uses: slackapi/slack-github-action@b0fa283ad8fea605de13dc3f449259339835fc52 # v2.1.0
+        uses: slackapi/slack-github-action@91efab103c0de0a537f72a35f6b8cda0ee76bf0a # v2.1.1
         with:
           method: chat.postMessage
           token: ${{ secrets.SLACK_BOUNDARY_TEST_BOT_TOKEN }}