chore(deps): update actions/checkout action to v4 (#98)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://github.com/actions/checkout) | action |
major | `v3` -> `v4` |

---

### Release Notes

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

###
[`v4`](https://github.com/actions/checkout/blob/HEAD/CHANGELOG.md#v400)

[Compare Source](https://github.com/actions/checkout/compare/v3...v4)

- [Support fetching without the --progress
option](https://github.com/actions/checkout/pull/1067)
-   [Update to node20](https://github.com/actions/checkout/pull/1436)

</details>

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.github/workflows/pullrequest.yml

@@ -23,7 +23,7 @@ jobs:
         php-version: ['8.0', '8.1', '8.2']
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: true
           fetch-depth: 0