Bump slackapi/slack-github-action from 3 to 4 (#237207)

Bumps [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action) from 3 to 4.
- [Release notes](https://github.com/slackapi/slack-github-action/releases)
- [Changelog](https://github.com/slackapi/slack-github-action/blob/main/CHANGELOG.md)
- [Commits](https://github.com/slackapi/slack-github-action/compare/v3...v4)

---
updated-dependencies:
- dependency-name: slackapi/slack-github-action
  dependency-version: '4'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/aglint.yml

@@ -100,7 +100,7 @@ jobs:
         )
       }}
     steps:
-      - uses: slackapi/slack-github-action@v3
+      - uses: slackapi/slack-github-action@v4
         with:
           webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
           webhook-type: incoming-webhook

.github/workflows/markdownlint.yml

@@ -61,7 +61,7 @@ jobs:
         )
       }}
     steps:
-      - uses: slackapi/slack-github-action@v3
+      - uses: slackapi/slack-github-action@v4
         with:
           webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
           webhook-type: incoming-webhook