ci: bump slackapi/slack-github-action from 2.1.1 to 3.0.1 (#794)

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

Author: dependabot[bot]

.github/workflows/follow-merge-upstream-repo-sync-v2.yml

@@ -246,7 +246,7 @@ jobs:
 
       - name: Send Slack Notification on failure
         if: failure()
-        uses: slackapi/slack-github-action@v2.1.1
+        uses: slackapi/slack-github-action@v3.0.1
         env:
           MENTION: "<@${{ steps.team_details.outputs.slack-user-id }}>"
           UPSTREAM_PR: "<${{ steps.upstream-prs.outputs.first_upstream_pr_url }}|upstream pr>, "