Update actions/checkout action to v4 (#213)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://github.com/actions/checkout) | action | major | `v2` -> `v4` |

---

### Release Notes

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

### [`v4`](https://github.com/actions/checkout/blob/HEAD/CHANGELOG.md#v414)

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

-   Disable `extensions.worktreeConfig` when disabling `sparse-checkout` by [@&#8203;jww3](https://github.com/jww3) in https://github.com/actions/checkout/pull/1692
-   Add dependabot config by [@&#8203;cory-miller](https://github.com/cory-miller) in https://github.com/actions/checkout/pull/1688
-   Bump the minor-actions-dependencies group with 2 updates by [@&#8203;dependabot](https://github.com/dependabot) in https://github.com/actions/checkout/pull/1693
-   Bump word-wrap from 1.2.3 to 1.2.5 by [@&#8203;dependabot](https://github.com/dependabot) in https://github.com/actions/checkout/pull/1643

### [`v3`](https://github.com/actions/checkout/blob/HEAD/CHANGELOG.md#v360)

[Compare Source](https://github.com/actions/checkout/compare/v2...v3)

-   [Fix: Mark test scripts with Bash'isms to be run via Bash](https://github.com/actions/checkout/pull/1377)
-   [Add option to fetch tags even if fetch-depth > 0](https://github.com/actions/checkout/pull/579)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

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---

This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
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Reviewed-on: #213
Co-authored-by: Renovate Bot <renovate@vylpes.com>
Co-committed-by: Renovate Bot <renovate@vylpes.com>

.forgejo/workflows/production.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: node
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Use Node.js
       uses: actions/setup-node@v1
       with:

.forgejo/workflows/stage.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: node
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Use Node.js
       uses: actions/setup-node@v1
       with:

.forgejo/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: node
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Use Node.js
       uses: actions/setup-node@v1
       with: