build-apk.yml fails due to deprecated action

Running `build-apk.yml` off a fresh fork produces this Github workflow error:

> **Annotations**
> _1 error_
> **Build PHANTO main branch**
> This request has been automatically failed because it uses a deprecated version of `actions/upload-artifact: v2`. Learn more: https://github.blog/changelog/2024-02-13-deprecation-notice-v1-and-v2-of-the-artifact-actions/
