chore(deps): update https://git.konstantinfickel.de/actions/checkout action to v6 (#22)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [https://git.konstantinfickel.de/actions/checkout](https://git.konstantinfickel.de/actions/checkout) | action | major | `v4` → `v6` |

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### Release Notes

<details>
<summary>actions/checkout (https://git.konstantinfickel.de/actions/checkout)</summary>

### [`v6`](https://git.konstantinfickel.de/actions/checkout/blob/HEAD/CHANGELOG.md#v602)

[Compare Source](https://git.konstantinfickel.de/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)

### [`v5`](https://git.konstantinfickel.de/actions/checkout/blob/HEAD/CHANGELOG.md#v501)

[Compare Source](https://git.konstantinfickel.de/actions/checkout/compare/v4...v5)

- Port v6 cleanup to v5 by [@&#8203;ericsciple](https://github.com/ericsciple) in [#&#8203;2301](https://github.com/actions/checkout/pull/2301)

</details>

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### Configuration

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Co-authored-by: kfickel <kfickel@noreply.git.konstantinfickel.de>
Reviewed-on: kfickel/streamer#22
Co-authored-by: Renovate Bot <renovate@konstantinfickel.de>
Co-committed-by: Renovate Bot <renovate@konstantinfickel.de>

.forgejo/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
 
     steps:
       - name: Check out Repository
-        uses: https://git.konstantinfickel.de/actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+        uses: https://git.konstantinfickel.de/actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
 
       - run: nix --version
       - run: nix flake check