Add workflow with cron for testing against WP nightly (#45260)

.github/workflows/nightly-tests.yml

@@ -0,0 +1,30 @@
+name: WP Nightly Tests
+on:
+  schedule:
+    - cron: '17 4 * * *' # Run at 4:17 AM UTC.
+  workflow_dispatch:
+
+permissions: {}
+
+jobs:
+  nightly:
+    name: Run Tests Against Nightly
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: 'actions/checkout@v3'
+        name: 'Checkout'
+        with:
+          fetch-depth: 0
+      - uses: './.github/actions/setup-woocommerce-monorepo'
+        name: 'Setup Monorepo'
+        id: 'setup-monorepo'
+        with:
+          install: '@woocommerce/plugin-woocommerce...'
+          build: '@woocommerce/plugin-woocommerce'
+      - name: 'Prepare Test Environment'
+        id: 'prepare-test-environment'
+        env:
+          WP_ENV_CORE: 'https://wordpress.org/nightly-builds/wordpress-latest.zip'
+        run: 'pnpm --filter="@woocommerce/plugin-woocommerce" env:test'
+      - name: 'Test'
+        run: 'pnpm --filter="@woocommerce/plugin-woocommerce" test:php:env'