Update coursier to 2.1.20 (#1780) #2345

Job	Run time
conformance	1m 41s
build (2_12, e2e)	3m 39s
build (2_12, test)	11m 34s
build (2_13, e2e)	4m 21s
build (2_13, test)	11m 12s
build (3, e2e)	4m 31s
build (3, test)	10m 22s
build (2_12, examples_and_formatting)	2m 39s
build (2_13, scala3_compat_test)	7m 32s
build (3, scala3_compat_test)	7m 48s
ci-passed	1s
	1h 5m 20s

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