Bumping upstream to 0.38

[bpetrikovics]

Bumping cadvisor to 0.38. Tried newer versions as well but on Pi 4B this was so far the only version that was both compiling and working. I also changed the way Dockerfile refers to the branch instead of tags, feel free to change that back if you don't agree.

Some error messages I was able to fix by adjusting the command line e.g.:

command:
  - '--raw_cgroup_prefix_whitelist=/docker/'
  - '--disable_metrics=hugetlb

Still complaining about smaps (Cannot read smaps files for any PID from CONTAINER), that might require further investigation.