chore(l2): report prover integration test failure to slack (#2503)

**Motivation**

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**Description**

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introduces -->

<!-- Link to issues: Resolves #111, Resolves #222 -->

Closes #issue_number

Author: jrchatruc

.github/workflows/main_prover.yaml

@@ -71,3 +71,12 @@ jobs:
       - name: Ensure admin permissions in _work
         if: always()
         run: sudo chown admin:admin -R /home/admin/actions-runner/_work/
+
+      - name: Report Status
+        if: always()
+        uses: ravsamhq/notify-slack-action@v2
+        with:
+          status: ${{ job.status }}
+          notify_when: 'failure'
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.ETHREX_L2_SLACK_WEBHOOK }}