Add --require-confirmation

I have 
```json
"deploy:stage": "AWS_REGION=eu-central-1 scandium update --name-postfix --stage",
"deploy:prod": "AWS_REGION=eu-central-1 scandium update --name-postfix --prod"
```

in my package.json, but it would be nice if i could add --require-confirmation or similar to the production one to avoid accidental deploys to production 🗡 