ci: bump the github-actions group with 2 updates

Bumps the github-actions group with 2 updates: [actions/github-script](https://github.com/actions/github-script) and [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action).


Updates `actions/github-script` from 7 to 8
- [Release notes](https://github.com/actions/github-script/releases)
- [Commits](actions/github-script@v7...v8)

Updates `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...v2.1.1)

---
updated-dependencies:
- dependency-name: actions/github-script
  dependency-version: '8'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: github-actions
- dependency-name: slackapi/slack-github-action
  dependency-version: 2.1.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: github-actions
...

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

Author: dependabot[bot]

.github/workflows/slack-open-prs-notification.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
       - name: Get open PRs
         id: open-prs
-        uses: actions/github-script@v7
+        uses: actions/github-script@v8
         with:
           script: |
             const { data: prs } = await github.rest.pulls.list({
@@ -40,7 +40,7 @@ jobs:
             );
 
       - name: Send open PRs summary to Slack
-        uses: slackapi/slack-github-action@v2.0.0
+        uses: slackapi/slack-github-action@v2.1.1
         with:
           webhook: ${{ secrets.SLACK_OPEN_PRS_WEBHOOK_URL }}
           webhook-type: webhook-trigger