Fix icalendar 6.0.0 breaking changes

Beta release for @duczz to test icalendar fixes

Fix updates

Fix update routine

Fix #60

Fixes #60

Fix for HA

Fixing #59

Fix for homeassistant warning

@joemcc-90 fixed the issue with the newest Homeassistant version,
Thanks!

Added regex

@vondraussen added regex, thanks

Renamed attributes to comply with new HA rule

20211212.01

changed versioning

Fixed async bug

Should fix #30

Merged async calls

merged #29 to make calls async and comply with HA

Added version key

Merge pull request #23 from jressel01/patch-1

Update manifest.json