🐳 Bump ubuntu in /ros2/testing/testing
🐳 Bump ubuntu in /ros2/testing/testing

Bumps ubuntu from focal-20210723 to focal-20210827.

---
updated-dependencies:
- dependency-name: ubuntu
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
ruffsl/docker_images,ruffsl/docker_images