chore(deps): update actions/setup-go action to v6 (#6)

This PR contains the following updates:

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

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### Release Notes

<details>
<summary>actions/setup-go (actions/setup-go)</summary>

### [`v6`](https://github.com/actions/setup-go/compare/v5...v6)

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

</details>

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### 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.

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 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

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Reviewed-on: #6
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/weekly.yaml

@@ -14,7 +14,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
       - name: Setup Go
-        uses: actions/setup-go@d35c59abb061a4a6fb18e82ac0862c26744d6ab5 # v5
+        uses: actions/setup-go@4dc6199c7b1a012772edbd06daecab0f50c9053c # v6
         with:
           go-version: "1.25.5"
       - name: Install yq