Update actions/checkout action to v4 (#4)

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This PR contains the following updates:

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

---

### Release Notes

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

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

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

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

</details>

---

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---

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.github/workflows/deploy.yml

@@ -7,7 +7,7 @@ jobs:
         runs-on: ubuntu-latest
         steps:
             - name: checkout source
-              uses: actions/checkout@v3
+              uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
 
             - name: Run chktex
               uses: xu-cheng/texlive-action/full@v1
@@ -19,7 +19,7 @@ jobs:
         runs-on: ubuntu-latest
         steps:
             - name: checkout source
-              uses: actions/checkout@v3
+              uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
 
             - name: Run Vale
               uses: errata-ai/vale-action@v2
@@ -35,7 +35,7 @@ jobs:
         runs-on: ubuntu-latest
         steps:
             - name: checkout source
-              uses: actions/checkout@v3
+              uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
 
             - name: Build PDF
               uses: xu-cheng/texlive-action/full@v1
@@ -83,7 +83,7 @@ jobs:
         needs: compile-latex
         steps:
             - name: checkout source
-              uses: actions/checkout@v3
+              uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
 
             - name: Download artefacts
               uses: actions/download-artifact@v3