Update GitHub Actions off deprecated Node.js 20 runtime

[ardelato]

Background

GitHub is deprecating the Node.js 20 runtime for Actions. The workflows below still pin actions that target Node 20, so the runner is currently force-running them on Node 24 — this shows up as a "Node.js 20 is deprecated" warning annotation on every run, and will eventually break once the Node 20 fallback is removed. Ref: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Affected actions (default branch hermes)

• actions/checkout@v4 → @v7 — build-image.yml
• aws-actions/configure-aws-credentials@v4 → @v6 — build-image.yml
• release-drafter/release-drafter@v5 → @v7 — release-drafter.yml

Acceptance

• No "Node.js 20 is deprecated" annotation on a fresh run of the affected workflow(s)
• Target versions are current latest majors (all run on Node 24); skim changelogs for checkout/upload-artifact/cache since they cross multiple majors