Traceback (most recent call last):
  File "/home/taziden/.local/bin/castero", line 5, in <module>
    from castero.__main__ import main
  File "/home/taziden/.local/pipx/venvs/castero/lib/python3.8/site-packages/castero/__main__.py", line 159, in <module>
    main()
  File "/home/taziden/.local/pipx/venvs/castero/lib/python3.8/site-packages/castero/__main__.py", line 92, in main
    import_subscriptions(vars(args)['import'], database)
  File "/home/taziden/.local/pipx/venvs/castero/lib/python3.8/site-packages/castero/__main__.py", line 27, in import_subscriptions
    for generated in subscriptions.parse():
  File "/home/taziden/.local/pipx/venvs/castero/lib/python3.8/site-packages/castero/subscriptions.py", line 136, in parse
    feed = Feed(url=entry.attrib['xmlUrl'])
  File "/home/taziden/.local/pipx/venvs/castero/lib/python3.8/site-packages/castero/feed.py", line 83, in __init__
    self._validate_feed()
  File "/home/taziden/.local/pipx/venvs/castero/lib/python3.8/site-packages/castero/feed.py", line 179, in _validate_feed
    raise FeedStructureError("XML document is not an RSS feed")
castero.feed.FeedStructureError: XML document is not an RSS feed