[ical4j 4.x] Test with Purelymail

[rfc2822]

Created from checklist item in #241.

Original text:

Purelymail

[cketti]

Tested with an Android 13 emulator.

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