notify slack on nightly build

.github/workflows/test.yml

@@ -8,6 +8,8 @@ on:
     - cron: '15 12 * * *'
 jobs:
   make:
+    environment:
+      TERM: xterm-256color
     permissions:
       contents: read
     runs-on: ${{ matrix.os }}
@@ -74,3 +76,12 @@ jobs:
             echo "Failed to bring up site"
             exit 1
           fi
+
+      - name: Notify Slack on nightly test failure
+        if: failure() && github.event_name == 'schedule'
+        run: |-
+          curl -s -o /dev/null -XPOST $SLACK_WEBHOOK_URL -d '{
+            "text": "🚨 Scheduled job failed! Click to view the run: <${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}|GitHub Actions Run>",
+          }'
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}