ci: upgrade checkout/setup-node to Node 24 (v5)

[xbow-bot]

Summary

Moves the CI workflow off the deprecated Node.js 20 runtime by upgrading the GitHub Actions to their Node 24 (v5) releases:

• actions/checkout v3.6.0 → v5.0.1
• actions/setup-node v3.9.1 → v5.0.0

SHA pins are retained and updated to the corresponding v5 commit SHAs, preserving the pinning introduced by the open 'CI/CD Security Improvements with Step Security' PR. This PR is stacked on top of that branch (chore/GHA-142316-stepsecurity-remediation) so the harden-runner step and permissions: block are kept — it complements, rather than duplicates, that work.

Verification

• Workflow YAML parses (yaml.safe_load).
• v5 tags resolved to commit SHAs via the GitHub API (lightweight tags → commit).

Generated by Claude Code Service (see job).
Respond to this PR with the prefix "Claude: " to trigger an action on this PR.

[daniel-xbow]

Claude: why do these build_nodejs tests fail? fix.

[xbow-bot]

Fixed the failing build_nodejs tests

Root cause: The failures were not in this PR's action-version bump nor in docker-modem's own tests (those pass — 18 passing). They occurred in the Dockerode test suite step, where two known-flaky BuildKit integration tests in the external dockerode repo time out after 60s:

• #followProgress › should follow BuildKit build progress
• #docker › should build image with buildKit

master already guards against these via a skip conditional (added in PR #3), but this branch descends from a pre-PR#3 state (through the fix-memory-leak merge) and had lost that guard, so all four matrix lanes ran the flaky BuildKit tests and failed.

Fix: Restored master's exact BuildKit-skip conditional in the Dockerode test suite step so the 14.x/16.x/18.x/19.x lanes exclude the BuildKit tests (--grep "buildKit|BuildKit" --invert):

if [ "${{ matrix.node-version }}" = "14.x" ] || ... ; then
  npm test -- --grep "buildKit|BuildKit" --invert
else
  npm test
fi

The Node 24 SHA-pinned actions/checkout@v5.0.1 and actions/setup-node@v5.0.0 upgrades and the harden-runner step are untouched. Workflow YAML validated (parses OK) and docker-modem's own test suite passes locally.

Generated by Claude Code Service (see job).