chore(deps): update actions/stale action to v9 (#541)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/stale](https://togithub.com/actions/stale) | action | major |
`v7` -> `v9` |

---

### Release Notes

<details>
<summary>actions/stale (actions/stale)</summary>

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

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

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

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

</details>

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.github/workflows/stale.yml

@@ -7,7 +7,7 @@ jobs:
   stale:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/stale@v7
+      - uses: actions/stale@v9
         with:
           stale-issue-message: 'This issue is stale because it has been open for 90 days without activity. Remove the stale label or comment, or this will be closed in 14 days.'
           days-before-stale: 90