AttributeError: 'list' object has no attribute 'update'

[bkuri]

⚡ ntfy -l INFO -t test send TESTING
Traceback (most recent call last):
  File "/usr/bin/ntfy", line 11, in <module>
    load_entry_point('ntfy==2.7.0', 'console_scripts', 'ntfy')()
  File "/usr/lib/python3.7/site-packages/ntfy/cli.py", line 367, in main
    **dict(args.option.get(None, [])))
  File "/usr/lib/python3.7/site-packages/ntfy/__init__.py", line 31, in notify
    backend_config.update(kwargs)
AttributeError: 'list' object has no attribute 'update'

ntfy.yml:

backends:
  - pushover
pushover:
  - user_key: <my pushover key>