Bump slackapi/slack-github-action from 2.0.0 to 2.1.0

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] <support@github.com>

Author: dependabot[bot]

.github/workflows/pr-notifier.yml

@@ -89,7 +89,7 @@ jobs:
             }
 
       - name: Post to Slack
-        uses: slackapi/slack-github-action@v2.0.0
+        uses: slackapi/slack-github-action@v2.1.0
         if: github.event.action != 'submitted' || github.event.review.state == 'approved'
 
         with: