ci: bump slackapi/slack-github-action from 2.0.0 to 2.1.1

Bumps [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action) from 2.0.0 to 2.1.1.
- [Release notes](https://github.com/slackapi/slack-github-action/releases)
- [Commits](slackapi/slack-github-action@v2.0.0...v2.1.1)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/slack-issue-notification.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Send issue details to Slack
-        uses: slackapi/slack-github-action@v2.0.0
+        uses: slackapi/slack-github-action@v2.1.1
         with:
           webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
           webhook-type: webhook-trigger