Build failing as `actions/upload-artifact: v3` is deprecated

It looks like the build is failing:

ref: https://github.com/opennextjs/docs/actions/runs/13070711154/job/36471553184

```
Error: This request has been automatically failed because it uses a deprecated version of `actions/upload-artifact: v3`. Learn more: https://github.blog/changelog/2024-04-16-deprecation-notice-v3-of-the-artifact-actions/
```