Pin icu_calendar to v2.1 #2179

Job	Run time
Lint	3m 43s
Test FFI (stable, ubuntu-latest)	1m 22s
Test feature matrix	11m 48s
Test (stable, macos-latest)	58s
Test (stable, windows-latest)	2m 0s
Documentation	31s
MSRV	23s
Test (stable, ubuntu-latest)	44s
	21m 29s

Provide feedback