chore(deps): update actions/checkout action to v6 (#40)

This PR contains the following updates:

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

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### Release Notes

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

### [`v6`](https://github.com/actions/checkout/blob/HEAD/CHANGELOG.md#v602)

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

- Fix tag handling: preserve annotations and explicit fetch-tags by [@&#8203;ericsciple](https://github.com/ericsciple) in [#&#8203;2356](https://github.com/actions/checkout/pull/2356)

</details>

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Reviewed-on: #40
Reviewed-by: t.behrendt <t.behrendt@noreply.localhost>
Co-authored-by: Renovate Bot <renovate@t00n.de>
Co-committed-by: Renovate Bot <renovate@t00n.de>

.gitea/workflows/deploy.yaml

@@ -141,7 +141,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: check-changes
     steps:
-      - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
       - uses: azure/setup-kubectl@776406bce94f63e41d621b960d78ee25c8b76ede # v4
       - uses: azure/k8s-set-context@ae59a723ba9abe7a9655538854a025448dbab4aa # v4
         with: