chore(deps): update https://code.forgejo.org/actions/checkout action to v6 (#6)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [https://code.forgejo.org/actions/checkout](https://code.forgejo.org/actions/checkout) | action | major | `v4` → `v6` |

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### Release Notes

<details>
<summary>actions/checkout (https://code.forgejo.org/actions/checkout)</summary>

### [`v6`](https://code.forgejo.org/actions/checkout/blob/HEAD/CHANGELOG.md#v602)

[Compare Source](https://code.forgejo.org/actions/checkout/compare/v5...v6)

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

### [`v5`](https://code.forgejo.org/actions/checkout/blob/HEAD/CHANGELOG.md#v501)

[Compare Source](https://code.forgejo.org/actions/checkout/compare/v4...v5)

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

</details>

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Reviewed-on: https://git.qtekfun.net/God/homelab-2026/pulls/6
Co-authored-by: renovate-bot <qtekfun+renobot@gmail.com>
Co-committed-by: renovate-bot <qtekfun+renobot@gmail.com>

Author: renovate-bot

.forgejo/workflows/deploy.yml

@@ -11,7 +11,7 @@ jobs:
       services: ${{ steps.diff.outputs.services }}
       has_changes: ${{ steps.diff.outputs.has_changes }}
     steps:
-      - uses: https://code.forgejo.org/actions/checkout@v4
+      - uses: https://code.forgejo.org/actions/checkout@v6
         with:
           fetch-depth: 2