Add Cairo update check workflow

.github/workflows/cairo-update-check.yml

@@ -0,0 +1,50 @@
+name: Cairo Update Check
+
+on:
+  push: # TODO this is just for testing
+  workflow_dispatch:
+    inputs:
+      slack:
+        description: "Send Slack notification on failure"
+        type: boolean
+        default: true
+  schedule:
+    - cron: '0 0 * * *'
+
+concurrency:
+  group: ${{ github.workflow }}
+  cancel-in-progress: true
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: software-mansion/setup-scarb@v1
+
+      - name: Build xtasks
+        run: cargo build -p xtask
+
+      - name: Upgrade Cairo to latest main commit
+        run: |
+          CAIRO_REV=$(git ls-remote --refs "https://github.com/starkware-libs/cairo" main | awk '{print $1}')
+          echo "::notice::https://github.com/starkware-libs/cairo/commit/$CAIRO_REV"
+          cargo xtask set-cairo-version --rev "$CAIRO_REV"
+
+      - run: cargo test --profile=ci --no-fail-fast
+
+  notify_failed:
+    runs-on: ubuntu-latest
+    if: always() && !(inputs.slack) && needs.check.result == 'failure'
+    needs: check
+    steps:
+      - name: Notify the team about workflow failure
+        uses: slackapi/[email protected]
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_CAIRO_UPDATE_CHECK_FAILURE_WEBHOOK_URL }}
+        with:
+          payload: |
+            {
+              "url": "${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+            }