chore(deps): update actions/checkout action to v6 (#43)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://github.com/actions/checkout) | action | major | `v4` -> `v6` |

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### 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)

### [`v5`](https://github.com/actions/checkout/compare/v4...v5)

[Compare Source](https://github.com/actions/checkout/compare/v4...v5)

</details>

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### 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

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This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
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Reviewed-on: #43
Co-authored-by: Renovate Bot <renovate@horstenkamp.eu>
Co-committed-by: Renovate Bot <renovate@horstenkamp.eu>

.gitea/workflows/lint.yaml

@@ -10,7 +10,7 @@ jobs:
     env:
       SPECIFIC_BRANCH: chore/update-pre-commit
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: actions/setup-python@v6
     - run: pip install pre-commit
       shell: bash