chore(deps): update actions/checkout action to v5 (#53)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://github.com/actions/checkout) | action | major | `v4` -> `v5` |
| [actions/checkout](https://github.com/actions/checkout) | action | major | `v4.2.2` -> `v5` |

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### Release Notes

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

### [`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 - Only on Sunday and Saturday ( * * * * 0,6 ) (UTC), Automerge - Between 12:00 AM and 03:59 AM ( * 0-3 * * * ) (UTC).

🚦 **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 these updates 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).
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Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-on: https://gitea.com/gitea/helm-actions/pulls/53
Reviewed-by: techknowlogick <techknowlogick@noreply.gitea.com>
Reviewed-by: DaanSelen <daanselen@noreply.gitea.com>
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Renovate Bot <renovate-bot@gitea.com>
Co-committed-by: Renovate Bot <renovate-bot@gitea.com>

.gitea/workflows/shellcheck.yml

@@ -9,6 +9,6 @@ jobs:
   shellcheck:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4.2.2
+      - uses: actions/checkout@v5
       - run: apt update --yes && apt install --yes shellcheck
       - run: find . -type f -name "*.sh" -exec shellcheck -a {} \;