Workflows: switch from hub to gh #1923

Job	Run time
build (2_12, mima)	1m 33s
build (2_12, e2e)	4s
build (2_12, test)	15m 10s
build (2_13, mima)	1m 32s
conformance	2m 42s
build (2_13, e2e)	5s
build (2_13, test)	10m 4s
build (3, mima)	5s
build (3, e2e)	5s
build (3, test)	12m 6s
build (2_12, examples_and_formatting)	3m 32s
build (2_13, scala3_compat_test)	11m 53s
build (3, scala3_compat_test)	11m 56s
ci-passed	1s
	1h 10m 48s

Provide feedback