bump node alpine to version 18 (LTS) (#45643)
Updating node version to LTS https://nodejs.org/
I tested locally and deploying to Google Cloud Run and build and deploy steps were successful in both cases.
## Documentation / Examples
- [x] Make sure the linting passes by running `pnpm build && pnpm lint`
- [x] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)
