Add more deploy triggers

Adds the following deploy triggers:

• Manual deploy
• Scheduled deploy (Deploy the site every day so we get the latest version of Primer packages)

.github/workflows/deploy.yml

 name: Deploy
 
 on:
+  # Manual deploy
+  workflow_dispatch:
+  # Scheduled deploy
+  schedule: 
+    - cron: '0 0 * * *' # Every day at midnight UTC time
+  # Deploy on change to main
   push:
     branches:
       - main