chore: update GitHub artifact client

[kzantow]

This PR updates the @actions/artifact library to the most recent version, which includes some usage updates.

See test runs here:

• https://github.com/kzantow-anchore/sbom-action-test/actions/runs/8943293414/job/24567681706#step:4:17
  • Artifacts attached: https://github.com/kzantow-anchore/sbom-action-test/actions/runs/8943293414
  • Snapshot successful: https://github.com/kzantow-anchore/sbom-action-test/actions/runs/8943293414/job/24567681706#step:4:979
• Release asset attached:
  • Current workflow list succeeded: https://github.com/kzantow-anchore/sbom-action-test/actions/runs/8943319048/job/24567762793#step:2:752
  • Asset attached: https://github.com/kzantow-anchore/sbom-action-test/releases/tag/v15 ... I think that covers the attachment integration points. And, of course, there are tests (but it's hard to ensure these are compatible with actual GitHub behavior -- any suggestions for how to improve testing here would be much appreciated!)

Fixes: #434