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](slackapi/slack-github-action@37ebaef...485a9d4)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/backport.yml

@@ -63,7 +63,7 @@ jobs:
           secrets: |-
             kv/data/teams/nomad/slack-webhooks feed-nomad | SLACK_FEED_NOMAD ;
       - name: Send slack notification on failure
-        uses: slackapi/slack-github-action@37ebaef184d7626c5f204ab8d3baff4262dd30f0 # v1.27.0
+        uses: slackapi/slack-github-action@485a9d42d3a73031f12ec201c457e2162c45d02d # v2.0.0
         with:
           payload: |
             {