Add setup-sbt to conformance #2363

Job	Run time
conformance	2m 14s
build (2_12, e2e)	3m 41s
build (2_12, test)	13m 21s
build (2_13, e2e)	4m 36s
build (2_13, test)	8m 47s
build (3, e2e)	4m 38s
build (3, test)	9m 36s
build (2_12, examples_and_formatting)	2m 58s
build (2_13, scala3_compat_test)	10m 6s
build (3, scala3_compat_test)	8m 29s
ci-passed	1s
	1h 8m 27s

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