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.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.92%. Comparing base (62e3894) to head (7163476).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #86   +/-   ##
=======================================
  Coverage   72.92%   72.92%           
=======================================
  Files          12       12           
  Lines         181      181           
  Branches       21       21           
=======================================
  Hits          132      132           
  Misses         37       37           
  Partials       12       12           

Flag	Coverage Δ
unittests	72.92% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.