Bump actions/download-artifact from 3 to 4.1.7 in /.github/workflows

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 3 to 4.1.7.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](https://github.com/actions/download-artifact/compare/v3...v4.1.7)

---
updated-dependencies:
- dependency-name: actions/download-artifact
dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Replace screenshot API with automatic action to generate screenshot

GitHub actions is very confusing. I wish I could preview actions before committing them.

- Although relative URLs work in the context of a repository, it results in a broken image when featured on a GitHub profile.
- The fix is to specify the URL in full, the only downside being that migrating this repo in future would take extra work.
- Given no other Git provider is currently doing this as far as I know, hopefully this won't be a problem.