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)

v6.0.3

Compare Source

• Fix checkout init for SHA-256 repositories by @​yaananth in #​2439
• fix: expand merge commit SHA regex and add SHA-256 test cases by @​yaananth in #​2414

v6.0.2

Compare Source

• Fix tag handling: preserve annotations and explicit fetch-tags by @​ericsciple in #​2356

v6.0.1

Compare Source

v6.0.0

Compare Source

v6

Compare Source

---

Configuration

📅 Schedule: (UTC)

• 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.