Update actions/stale action to v9

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
actions/stale	action	major	v8 -> v9

---

Release Notes

actions/stale (actions/stale)

### [`v9`](https://togithub.com/actions/stale/compare/v8...v9) [Compare Source](https://togithub.com/actions/stale/compare/v8...v9)

---

Configuration

📅 Schedule: Branch creation - "before 4am on the first day of the month" (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 has been generated by Mend Renovate. View repository job log here.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (d769323) 94.49% compared to head (59126cf) 94.49%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #326 +/- ## ======================================= Coverage 94.49% 94.49% ======================================= Files 36 36 Lines 962 962 ======================================= Hits 909 909 Misses 53 53 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.