Use Node 24-native cache action

[bluk1020]

Summary

• update setup-nub's internal cache step from actions/cache@v4 to actions/cache@v6
• keep setup-nub caching enabled while moving the underlying cache action onto the Node 24 runtime

Why

actions/cache@v4 declares using: node20, which now produces GitHub Actions Node.js 20 deprecation warnings when setup-nub caching is enabled. actions/cache@v6 declares using: node24 with the same inputs/outputs used by setup-nub here.

Validation

• Parsed action.yml and all workflows with Ruby YAML
• Confirmed action.yml contains actions/cache@v6 and no actions/cache@v4
• Confirmed upstream actions/cache@v6 metadata declares using: node24
• git diff --check
• Ran actionlint; existing smoke workflow shellcheck warnings are unchanged from origin/main

[pullfrog]

✅ No new issues found.

Reviewed changes — a one-line bump of setup-nub's internal cache step from actions/cache@v4 to actions/cache@v6 to move off the deprecated Node 20 runtime.

• Bump actions/cache v4 → v6 — action.yml:252 now pins actions/cache@v6, whose action.yml declares using: 'node24', eliminating GitHub's Node 20 deprecation warnings emitted by v4 (using: node20) when caching is enabled.

I verified compatibility against the v6 tag directly rather than main: setup-nub consumes only path, key, and restore-keys (inputs) plus the cache-hit output (re-exported at action.yml:78 and asserted in .github/workflows/smoke.yml). All of these are present and unchanged at actions/cache@v6, so the bump is functionally transparent for this usage.

ℹ️ actions/cache v5+ drops the legacy v1 cache service

actions/cache v5 and later use the v2 cache backend exclusively; the legacy Azure-backed v1 service is no longer supported. On github.com-hosted runners this is a non-issue. It can matter for consumers running on older GitHub Enterprise Server versions whose cache service doesn't yet expose the v2 API — for them, v6 would fail to save/restore. No change requested; flagging for awareness since setup-nub is a published, externally consumed action.

  ^{｜ View workflow run ｜ Using Claude Opus ｜ 𝕏}