chore(deps): bump slackapi/slack-github-action from 1.27.0 to 2.0.0

Bumps [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action) from 1.27.0 to 2.0.0.
- [Release notes](https://github.com/slackapi/slack-github-action/releases)
- [Commits](https://github.com/slackapi/slack-github-action/compare/v1.27.0...v2.0.0)

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

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

.github/workflows/upload-assets-to-cdn.yml

@@ -74,7 +74,7 @@ jobs:
           gcloud storage cp --cache-control='public,max-age=86400' --content-disposition=attachment -r assets/legal/* gs://fxa-content-cdn-prod-distbucket/legal/
 
       - name: "Post to fxa-team Slack channel"
-        uses: slackapi/slack-github-action@v1.27.0
+        uses: slackapi/slack-github-action@v2.0.0
         with:
           channel-id: 'CLV3KMZ8B'
           slack-message: "New assets have been uploaded to CDN: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"