Update actions/checkout action to v6 (#24)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://github.com/actions/checkout) | action | major | `v5` -> `v6` |

---

### Release Notes

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

### [`v6`](https://github.com/actions/checkout/compare/v5...v6)

[Compare Source](https://github.com/actions/checkout/compare/v5...v6)

</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.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0Mi4xOS4wIiwidXBkYXRlZEluVmVyIjoiNDIuMTkuMCIsInRhcmdldEJyYW5jaCI6Im5leHQiLCJsYWJlbHMiOltdfQ==-->

Reviewed-on: #24
Co-authored-by: Renovate Bot <renovate-bot@valverde.cloud>
Co-committed-by: Renovate Bot <renovate-bot@valverde.cloud>

.gitea/workflows/lint.yaml

@@ -9,7 +9,7 @@ jobs:
       - name: Setup Bun
         uses: oven-sh/setup-bun@v2
       - name: Clone repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install dependencies
         run: bun install --frozen-lockfile
       - name: Lint TypeScript