Bump docker/build-push-action from 4.1.1 to 4.2.1

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] <[email protected]>

.github/workflows/ci.yaml

@@ -110,7 +110,7 @@ jobs:
         uses: docker/setup-buildx-action@v2
 
       - name: Build and push
-        uses: docker/build-push-action@v4.1.1
+        uses: docker/build-push-action@v4.2.1
         with:
           build-args: |-
             KEYCLOAK_VERSION=${{ matrix.env.KEYCLOAK_VERSION }}