chore(deps): update docker/setup-buildx-action action to v3 (#28)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action) | action | major | `v2` -> `v3` |

---

### Release Notes

<details>
<summary>docker/setup-buildx-action (docker/setup-buildx-action)</summary>

### [`v3`](https://github.com/docker/setup-buildx-action/compare/v2...v3)

[Compare Source](https://github.com/docker/setup-buildx-action/compare/v2...v3)

</details>

---

### 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.

---

 - [ ] <!-- 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).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzOS4yMzguMiIsInVwZGF0ZWRJblZlciI6IjM5LjIzOC4yIiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6W119-->

Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-authored-by: t.behrendt <t.behrendt@noreply.localhost>
Reviewed-on: #28
Co-authored-by: Renovate Bot <renovate@t00n.de>
Co-committed-by: Renovate Bot <renovate@t00n.de>

.gitea/workflows/cd.yaml

@@ -68,7 +68,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v2
+        uses: docker/setup-buildx-action@v3
 
       - name: Login to Registry
         uses: docker/login-action@v2