[Repo Assist] ci: align docs.yaml action versions with rest of workflows

[github-actions]

🤖 This is an automated pull request from Repo Assist.

Closes #361

Summary

docs.yaml was the only workflow using outdated action versions. This updates it to match every other workflow in the repository:

Action	Before	After
actions/checkout	@v4	@v6
actions/cache	@v4	@v5

build.yaml, test.yaml, main.yaml, and publish.yaml all already use @v6/@v5. This eliminates version drift and ensures the docs workflow benefits from the same improvements.

Test Status

No application code changed — workflow YAML only. The docs workflow is not runnable in a PR, but the changes are minimal (version bumps only matching the pattern already working in all other workflows).

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Warning

🛡️ Protected Files — Push Permission Denied

This was originally intended as a pull request, but the patch modifies protected files: .github/workflows/docs.yaml.

The push was rejected because GitHub Actions does not have workflows permission to push these changes, and is never allowed to make such changes, or other authorization being used does not have this permission. A human must create the pull request manually.

To create a pull request with the changes:

# Download the patch from the workflow run
gh run download 23468385436 -n agent-artifacts -D /tmp/agent-artifacts-23468385436

# Create a new branch
git checkout -b repo-assist/ci-docs-action-versions-20260324-46d2ba8f34e6b85e main

# Apply the patch (--3way handles cross-repo patches)
git am --3way /tmp/agent-artifacts-23468385436/aw-repo-assist-ci-docs-action-versions-20260324.patch

# Push the branch and create the pull request
git push origin repo-assist/ci-docs-action-versions-20260324-46d2ba8f34e6b85e
gh pr create --title '[Repo Assist] ci: align docs.yaml action versions with rest of workflows' --base main --head repo-assist/ci-docs-action-versions-20260324-46d2ba8f34e6b85e --repo fsprojects/FSharp.Control.TaskSeq

Generated by Repo Assist · ◷

To install this agentic workflow, run

gh aw add githubnext/agentics/workflows/repo-assist.md@4957663821dbb3260348084fa2f1659701950fef