Squashed 'external/workload-automation/' changes from 8647ceaf..f8908e81

f8908e81 Dockerfile: Update to newer base and Python version
dd44d6fa docs/api/workload: Update documentation for `activity` attribute
753786a4 fw/workload: Add `activity` attribute to APK workloads

git-subtree-dir: external/workload-automation
git-subtree-split: f8908e81947d283446682aaff2105aa8b6c13288