Build the tutorial nightly to get alerts if it fails

.github/workflows/verify-site-builds.yml

@@ -0,0 +1,31 @@
+name: Verify site builds
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 2 * * *'
+
+jobs:
+  test:
+    name: Bu
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout source
+        uses: actions/checkout@v3
+      - name: Install dependencies
+        run: pip install -r requirements.txt
+        env:
+          INSIDERS_PAT: ${{ secrets.MATERIAL_INSIDERS_ACCESS }}
+      - name: Building site
+        run: mkdocs build
+      - name: Send alert on failure
+        if: ${{ failure() }}
+        uses: zulip/github-actions-zulip/send-message@b62d5a0e48a4d984ea4fce5dd65ba691963d4db4
+        with:
+          api-key: ${{ secrets.ZULIP_SCHEDULED_JOB_FAILURE_API_KEY }}
+          email: ${{ secrets.ZULIP_SCHEDULED_JOB_FAILURE_EMAIL }}
+          organization-url: 'https://ponylang.zulipchat.com/'
+          to: notifications
+          type: stream
+          topic: ${{ github.repository }} scheduled job failure
+          content: ${{ github.server_url}}/${{ github.repository }}/actions/runs/${{ github.run_id }} failed.