`make lint` failed because of
```
lint run-test: commands[0] | flake8
Traceback (most recent call last):
File "/tmp/charm-fstab-config/src/.tox/lint/bin/flake8", line 8, in <module>
sys.exit(main())
File "/tmp/charm-fstab-config/src/.tox/lint/lib/python3.10/site-packages/flake8/main/cli.py", line 23, in main
app.run(argv)
File "/tmp/charm-fstab-config/src/.tox/lint/lib/python3.10/site-packages/flake8/main/application.py", line 198, in run
self._run(argv)
File "/tmp/charm-fstab-config/src/.tox/lint/lib/python3.10/site-packages/flake8/main/application.py", line 186, in _run
self.initialize(argv)
File "/tmp/charm-fstab-config/src/.tox/lint/lib/python3.10/site-packages/flake8/main/application.py", line 165, in initialize
self.plugins, self.options = parse_args(argv)
File "/tmp/charm-fstab-config/src/.tox/lint/lib/python3.10/site-packages/flake8/options/parse_args.py", line 53, in parse_args
opts = aggregator.aggregate_options(option_manager, cfg, cfg_dir, rest)
File "/tmp/charm-fstab-config/src/.tox/lint/lib/python3.10/site-packages/flake8/options/aggregator.py", line 30, in aggregate_options
parsed_config = config.parse_config(manager, cfg, cfg_dir)
File "/tmp/charm-fstab-config/src/.tox/lint/lib/python3.10/site-packages/flake8/options/config.py", line 131, in parse_config
raise ValueError(
ValueError: Error code '#TODO' supplied to 'ignore' option does not match '^[A-Z]{1,3}[0-9]{0,3}$'
```
