chore(deps): update docker/build-push-action action to v6 (#2)

[![Mend
Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Type | Update | Change | OpenSSF |
|---|---|---|---|---|
|
[docker/build-push-action](https://togithub.com/docker/build-push-action)
| action | major | `v5` -> `v6` | [![OpenSSF
Scorecard](https://api.securityscorecards.dev/projects/github.com/docker/build-push-action/badge)](https://securityscorecards.dev/viewer/?uri=github.com/docker/build-push-action)
|

---

### Release Notes

<details>
<summary>docker/build-push-action (docker/build-push-action)</summary>

###
[`v6`](https://togithub.com/docker/build-push-action/compare/v5...v6)

[Compare
Source](https://togithub.com/docker/build-push-action/compare/v5...v6)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - "after 10pm every weekday,before 5am
every weekday,every weekend" (UTC), 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 [Mend
Renovate](https://www.mend.io/free-developer-tools/renovate/). View
repository job log
[here](https://developer.mend.io/github/settlemint/btp-smartcontractsets).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNy40MTMuMiIsInVwZGF0ZWRJblZlciI6IjM3LjQxMy4yIiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6WyJkZXBlbmRlbmNpZXMiXX0=-->

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/solidity.yml

@@ -207,7 +207,7 @@ jobs:
             type=sha
 
       - name: Build and push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         id: build-and-push
         with:
           platforms: linux/amd64,linux/arm64