KeyError: 'throttle.io_service_bytes in container python:3.8.17-slim

[yli02]

Hi, thanks for providing this library. I unfortunately got the following error while running inside docker container which is given in the title.

$ ./cgutil top -i -n 2 -b
Traceback (most recent call last):
  File "./cgutil", line 52, in <module>
    main()
  File "./cgutil", line 48, in main
    cmd.run()
  File "/app/.venv/lib/python3.8/site-packages/cgutils/commands/top.py", line 534, in run
    return self._run_window(None)
  File "/app/.venv/lib/python3.8/site-packages/cgutils/commands/top.py", line 530, in _run_window
    ui.run()
  File "/app/.venv/lib/python3.8/site-packages/cgutils/commands/top.py", line 330, in run
    self.cgstats.update()
  File "/app/.venv/lib/python3.8/site-packages/cgutils/commands/top.py", line 227, in update
    stats = self._convert[_cgroup.subsystem.name](stats)
  File "/app/.venv/lib/python3.8/site-packages/cgutils/commands/top.py", line 162, in __conv_blkio_stats
    for k, v in stats['throttle.io_service_bytes'].items():
KeyError: 'throttle.io_service_bytes