[Repo Assist] eng: update GitHub Actions to latest major versions (bundle)

[github-actions]

🤖 Repo Assist here — I'm an automated AI assistant. This PR was generated automatically.

Summary

Bundles pending GitHub Actions version updates across all workflow files:

Action	Before	After
actions/checkout	v5	v6 (v6.0.2)
actions/cache	v4	v5

Files updated: build.yaml, test.yaml, main.yaml, publish.yaml

Motivation

• actions/checkout@v6 is the current stable release.
• actions/cache@v5 upgrades to the Node.js 24 runtime (Dependabot PR build(deps): Bump actions/cache from 4 to 5 #323 already proposed this).

This PR supersedes Dependabot PR #323 — that PR can be closed once this is merged.

Test Status

These are CI configuration changes only — no library code is modified. The changes will be validated by CI on this PR.

🤖 Generated by Repo Assist · Task 4: Engineering Investments

Generated by Repo Assist · ◷

To install this agentic workflow, run

gh aw add githubnext/agentics/workflows/repo-assist.md@346204513ecfa08b81566450d7d599556807389f

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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/build.yaml, .github/workflows/main.yaml, .github/workflows/publish.yaml, .github/workflows/test.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 22919660721 -n agent-artifacts -D /tmp/agent-artifacts-22919660721

# Create a new branch
git checkout -b repo-assist/eng-bundle-action-updates-2026-03-10-41bd9ade33e0bbe5 main

# Apply the patch (--3way handles cross-repo patches)
git am --3way /tmp/agent-artifacts-22919660721/aw-repo-assist-eng-bundle-action-updates-2026-03-10.patch

# Push the branch and create the pull request
git push origin repo-assist/eng-bundle-action-updates-2026-03-10-41bd9ade33e0bbe5
gh pr create --title '[Repo Assist] eng: update GitHub Actions to latest major versions (bundle)' --base main --head repo-assist/eng-bundle-action-updates-2026-03-10-41bd9ade33e0bbe5 --repo fsprojects/FSharp.Control.TaskSeq