chore(deps): update actions/checkout action to v4 (#11)

This PR contains the following updates:

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

---

### Release Notes

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

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

[Compare Source](https://github.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 https://github.com/actions/checkout/pull/1739
-   Bump actions/checkout from 3 to 4 by [@&#8203;dependabot](https://github.com/dependabot) in https://github.com/actions/checkout/pull/1697
-   Check out other refs/\* by commit by [@&#8203;orhantoy](https://github.com/orhantoy) in https://github.com/actions/checkout/pull/1774
-   Pin actions/checkout's own workflows to a known, good, stable version. by [@&#8203;jww3](https://github.com/jww3) in https://github.com/actions/checkout/pull/1776

</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:eyJjcmVhdGVkSW5WZXIiOiIzNy40MjQuMyIsInVwZGF0ZWRJblZlciI6IjM3LjQyNC4zIiwidGFyZ2V0QnJhbmNoIjoibWFzdGVyIiwibGFiZWxzIjpbXX0=-->

Co-authored-by: Renovate Bot <renovate-bot@gitea.com>
Reviewed-on: #11

.gitea/workflows/push.yaml

@@ -6,7 +6,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
         with:
           go-version: "1.22"