ci(github-action): update actions/checkout action to v4.2.1

[renovate]

This PR contains the following updates:

Package	Type	Update	Change	OpenSSF
actions/checkout	action	patch	v4.2.0 -> v4.2.1

---

Release Notes

actions/checkout (actions/checkout)

v4.2.1

Compare Source

• Check out other refs/* by commit if provided, fall back to ref by @​orhantoy in https://github.com/actions/checkout/pull/1924

---

Configuration

📅 Schedule: Branch creation - "before 4am" (UTC), 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 76.12%. Comparing base (ab72068) to head (c1a6732).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #338   +/-   ##
=======================================
  Coverage   76.12%   76.12%           
=======================================
  Files          52       52           
  Lines         980      980           
  Branches       61       61           
=======================================
  Hits          746      746           
  Misses        221      221           
  Partials       13       13           

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