Update actions/stale action to v8

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/stale](https://github.com/actions/stale) | action | major | `v7` -> `v8` |

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### Release Notes

<details>
<summary>actions/stale</summary>

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

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

</details>

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### 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.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

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.github/workflows/stale.yml

@@ -8,7 +8,7 @@ jobs:
   stale:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/stale@v7
+      - uses: actions/stale@v8
         with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           close-issue-message: >