chore(deps): update actions/checkout action to v4 (#18)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://gitea.ocram85.com/actions/checkout) | action | major | `v3` -> `v4` |

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### Release Notes

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

### [`v4`](https://gitea.ocram85.com/actions/checkout/blob/HEAD/CHANGELOG.md#v417)

[Compare Source](https://gitea.ocram85.com/actions/checkout/compare/v3...v4)

-   Bump the minor-npm-dependencies group across 1 directory with 4 updates by [@&#8203;dependabot](https://github.com/dependabot) in actions/checkout#1739
-   Bump actions/checkout from 3 to 4 by [@&#8203;dependabot](https://github.com/dependabot) in actions/checkout#1697
-   Check out other refs/\* by commit by [@&#8203;orhantoy](https://github.com/orhantoy) in actions/checkout#1774
-   Pin actions/checkout's own workflows to a known, good, stable version. by [@&#8203;jww3](https://github.com/jww3) in actions/checkout#1776

</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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Co-authored-by: OCram85 <marco.blessing@googlemail.com>
Reviewed-on: https://gitea.ocram85.com/OCram85/swarmproxy/pulls/18
Reviewed-by: OCram85 <marco.blessing@googlemail.com>
Co-authored-by: renovate-bot <renovate@ocram85.com>
Co-committed-by: renovate-bot <renovate@ocram85.com>

.gitea/workflows/release.yaml

@@ -9,7 +9,7 @@ jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-      - uses: https://gitea.ocram85.com/actions/checkout@v3
+      - uses: https://gitea.ocram85.com/actions/checkout@v4
         with:
           fetch-depth: 0
       - name: setup go