[ical4j 4.x] Test with Fastmail

[rfc2822]

Created from checklist item in #241.

Original text:

Fastmail

[cketti]

Tested with an Android 13 emulator and #313 applied.

• Event added on server syncs to device
• Event added on device syncs to server
• Event changed on server syncs to device
• Event changed on device syncs to server
• Recurring event with exception syncs fine both ways
• Task added on device syncs to server
• Task changed on device syncs to server
• Task deleted on device syncs to server