[PRMP-978] Fix daily health check cypress tests

Author: adamwhitingnhs

.github/workflows/cron-daily-health-check.yml

@@ -119,6 +119,9 @@ jobs:
           runTests: false
           build: npm run build
           working-directory: ./app
+
+      - name: Copy main.html to index.html for serve compatibility
+        run: cp ./app/build/main.html ./app/build/index.html
 
       - name: npm install serve -g
         run: npm install serve -g