Update actions/stale action to v8

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
actions/stale	action	major	v7 -> v8

---

Release Notes

actions/stale

### [`v8`](https://togithub.com/actions/stale/compare/v7...v8) [Compare Source](https://togithub.com/actions/stale/compare/v7...v8)

---

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 has been generated by Mend Renovate. View repository job log here.

[kitchen-porter]

Released as: 7.1.12