ci: bump slackapi/slack-github-action from 2.0.0 to 2.1.0 (#130)

Bumps [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/slackapi/slack-github-action/releases)
- [Commits](slackapi/slack-github-action@v2.0.0...v2.1.0)

---
updated-dependencies:
- dependency-name: slackapi/slack-github-action
  dependency-version: 2.1.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -66,7 +66,7 @@ jobs:
         env:
           FLY_API_TOKEN: ${{ secrets.FLY_API_TOKEN }}
       - if: failure()
-        uses: slackapi/slack-github-action@v2.0.0
+        uses: slackapi/slack-github-action@v2.1.0
         with:
           method: chat.postMessage
           token: ${{ secrets.SLACK_BOT_TOKEN }}