Bump docker/build-push-action from 5 to 6 (#18)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 5 to 6.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v5...v6)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
           path: src/cartesian_controllers_ros2
 
       - name: Build Docker Image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           tags: cartesian_controllers_ros2:humble
           file: .docker/ci/Dockerfile