One Node 20 deprecation warning in the docs workflow

[Onwcan]

What it is

The documentation workflow currently produces one Node 20 deprecation warning.

actions/upload-pages-artifact@v3 carries the Node 20 dependency transitively through actions/upload-artifact@v4.

Why it has not been cleared

Removing the warning requires moving to a newer major version of upload-pages-artifact.

That also means using a different pairing with deploy-pages from the combination currently used by GitHub's own Pages starter workflow.

That trade has intentionally not been made yet.

The current reasoning is documented beside the workflow line in:

.github/workflows/ci.yml:389

Acceptance criteria

• Check GitHub's current Pages starter workflow.
• Determine whether it has moved to a newer upload-pages-artifact / deploy-pages pairing.
• If GitHub's starter workflow has moved, update this repository to the same tested pairing.
• If GitHub's starter workflow has not moved, leave the warning in place.
• If leaving it in place, refresh the nearby comment with the date on which the pairing was last checked.

The starter workflow should remain the reference for which Pages action combination is actually tested together.

Note for whoever picks this up

An earlier investigation reached the wrong conclusion and claimed that upload-pages-artifact@v3 was not involved in the Node 20 deprecation.

The CI run showed otherwise.

The dependency is transitive.

Use the actual run log as the source of truth rather than relying only on the action's own README.