thank you @hmmbob for the pr
2021.12.0 has a bump of pychromecast, which changes the way you can retrieve Chromecast info.
home-assistant/core#59719
home-assistant/core#60205
With the changes in this PR I fixed the issue locally. It should be tested by others too.
Also implemented a fix for a warning on device_state_attributes while I was at it anyway - this is just a rename to extra_state_attributes
Fixes #269
Fixes #273
Fixes #274
Fixes custom-cards/spotify-card#170