Update actions/deploy-pages action to v2 (#112)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/deploy-pages](https://togithub.com/actions/deploy-pages) |
action | major | `v1` -> `v2` |

---

### Release Notes

<details>
<summary>actions/deploy-pages (actions/deploy-pages)</summary>

### [`v2`](https://togithub.com/actions/deploy-pages/compare/v1...v2)

[Compare
Source](https://togithub.com/actions/deploy-pages/compare/v1...v2)

</details>

---

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.github/workflows/pages.yml

@@ -66,4 +66,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v1
+        uses: actions/deploy-pages@v2