chore(deps): update actions/setup-buildx-action action to v3 (#21)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/setup-buildx-action](https://gitea.ocram85.com/actions/setup-buildx-action) | action | major | `v2` -> `v3` |

---

### Release Notes

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

### [`v3`](https://gitea.ocram85.com/actions/setup-buildx-action/compare/v2...v3)

[Compare Source](https://gitea.ocram85.com/actions/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:eyJjcmVhdGVkSW5WZXIiOiIzNy4xODkuMSIsInVwZGF0ZWRJblZlciI6IjM3LjE4OS4xIiwidGFyZ2V0QnJhbmNoIjoibWFpbiJ9-->

Co-authored-by: OCram85 <marco.blessing@googlemail.com>
Reviewed-on: https://gitea.ocram85.com/OCram85/swarmproxy/pulls/21
Reviewed-by: OCram85 <marco.blessing@googlemail.com>
Co-authored-by: renovate-bot <renovate@ocram85.com>
Co-committed-by: renovate-bot <renovate@ocram85.com>

.gitea/workflows/ci.yaml

@@ -31,7 +31,7 @@ jobs:
             type=semver,pattern={{major}}.{{minor}}
       -
         name: Set up Docker Buildx
-        uses: https://gitea.ocram85.com/actions/setup-buildx-action@v2
+        uses: https://gitea.ocram85.com/actions/setup-buildx-action@v3
       -
         name: Login to Gitea Package Registry
         uses: https://gitea.ocram85.com/actions/login-action@v2