build(deps): Bump docker/build-push-action from 4.1.1 to 4.2.1 (#1313)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 4.1.1 to 4.2.1.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v4.1.1...v4.2.1)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Sergio Mena <sergio@informal.systems>

.github/workflows/cometbft-docker.yml

@@ -51,7 +51,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Publish to Docker Hub
-        uses: docker/build-push-action@v4.1.1
+        uses: docker/build-push-action@v4.2.1
         with:
           context: .
           file: ./DOCKER/Dockerfile

.github/workflows/testapp-docker.yml

@@ -51,7 +51,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Publish to Docker Hub
-        uses: docker/build-push-action@v4.1.1
+        uses: docker/build-push-action@v4.2.1
         with:
           context: .
           file: ./test/e2e/docker/Dockerfile