Workflows: switch from hub to gh #1922

Job	Run time
build (2_12, mima)	1m 17s
build (2_12, e2e)	5s
build (2_12, test)	13m 11s
build (2_13, mima)	2m 1s
conformance	2m 17s
build (2_13, e2e)	8s
build (2_13, test)	13m 30s
build (3, mima)	5s
build (3, e2e)	8s
build (3, test)	11m 20s
build (2_12, examples_and_formatting)	4m 40s
build (2_13, scala3_compat_test)	11m 33s
build (3, scala3_compat_test)	10m 48s
ci-passed	1s
	1h 11m 4s

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