feat(github-action)!: Update actions/checkout action to v6

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v5 -> v6

---

Release Notes

actions/checkout (actions/checkout)

v6

Compare Source

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.

[github-actions]

🏷️ Test Badge Generation (Shields.io)

hilbert

hsv

step

step_invert

luminance

[github-actions]

🏷️ Test Badge Generation (Badgen.net)

hilbert

[Copilot]

Pull request overview

This PR updates the actions/checkout GitHub Action from v5 to v6 across all workflow files in the repository. The update is a dependency maintenance change generated by Renovate, following the project's security best practice of pinning actions to SHA digests. The PR title correctly follows the semantic commit convention feat(github-action)!: as configured in the Renovate settings for GitHub Actions major updates.

Key Changes:

• Updated actions/checkout SHA from 93cb6efe... (v5) to 1af3b93b... (v6)
• Applied consistently across 4 workflow file locations
• Maintained security-conscious SHA pinning with human-readable version comments

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
.github/workflows/render-all-badges.yaml	Updated checkout action to v6 in the badge rendering workflow
.github/workflows/pr-badge-comment.yml	Updated checkout action to v6 in the PR comment workflow
.github/workflows/build-and-test.yaml	Updated checkout action to v6 in three job steps (test, image, badgesort)