chore: migrate internal actions from node20 to node24 ahead of June 2026 deprecation

[mkabir-evertz]

Describe the bug
The reusable workflows in this repo (e.g. generator_generic_slsa3.yml) bundle
internal actions that use node20, which is deprecated. Users are seeing this
warning on every workflow run:

"Node.js 20 actions are deprecated. Actions will be forced to run with Node.js 24
by default starting June 2nd, 2026."

Affected actions:

• .github/actions/compute-sha256
• .github/actions/privacy-check
• actions/checkout (pinned SHA)
• actions/setup-go (pinned SHA)
• actions/upload-artifact (pinned SHA)

To Reproduce

1. Use any reusable workflow from this repo (e.g. generator_generic_slsa3.yml)
2. Run the workflow
3. Check the "Complete job" step output
4. See Node.js 20 deprecation warning

Expected behavior
No deprecation warnings. The workflows should use node24-compatible actions
before the June 2, 2026 deadline, after which node20 will be the default and
workflows may break. Node 20 will be fully removed from runners in fall 2026.

Screenshots

Additional context
GitHub deprecation announcement:
https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

[reggie-k]

Is this planned to be worked on?

[suzuki-shunsuke]

CI failed, but there is a update PR by Renovate.

• chore(deps): update github-actions (major) #4361

[jkreileder]

Looks like this has been pushed back to June 16th. Having a new release would be nice.

Warning: Node.js 20 actions are deprecated. The following actions are running on Node.js 20 
and may not work as expected: ./__BUILDER_CHECKOUT_DIR__/.github/actions/compute-sha256,
./__BUILDER_CHECKOUT_DIR__/.github/actions/privacy-check, 
actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683, actions/setup-
go@f111f3307d8850f501ac008e886eec1fd1932a34. Actions will be forced to run with Node.js 24 by 
default starting June 16th, 2026. Node.js 20 will be removed from the runner on September 16th, 
2026. Please check if updated versions of these actions are available that support Node.js 24. To
opt into Node.js 24 now, set the FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true environment variable on 
the runner or in your workflow file. Once Node.js 24 becomes the default, you can temporarily opt 
out by setting ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true. For more information see: 
https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/