Update actions/upload-pages-artifact action to v4 (#14)

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This PR contains the following updates:

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

---

### Release Notes

<details>
<summary>actions/upload-pages-artifact
(actions/upload-pages-artifact)</summary>

###
[`v4`](https://redirect.github.com/actions/upload-pages-artifact/compare/v3...v4)

[Compare
Source](https://redirect.github.com/actions/upload-pages-artifact/compare/v3...v4)

</details>

---

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.github/workflows/jekyll.yml

@@ -49,7 +49,7 @@ jobs:
           JEKYLL_ENV: production
       - name: Upload artifact
         # Automatically uploads an artifact from the './_site' directory by default
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v4
 
   # Deployment job
   deploy: