ci: github: bump actions/stale from 8 to 9

Bumps [actions/stale](https://github.com/actions/stale) from 8 to 9.
- [Release notes](https://github.com/actions/stale/releases)
- [Changelog](https://github.com/actions/stale/blob/main/CHANGELOG.md)
- [Commits](actions/stale@v8...v9)

---
updated-dependencies:
- dependency-name: actions/stale
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: Benjamin Cabé <[email protected]>

Author: kartben

.github/workflows/stale_issue.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-22.04
     if: github.repository == 'zephyrproject-rtos/zephyr'
     steps:
-    - uses: actions/stale@v8
+    - uses: actions/stale@v9
       with:
         stale-pr-message: 'This pull request has been marked as stale because it has been open (more
           than) 60 days with no activity. Remove the stale label or add a comment saying that you