ci(mergify): upgrade configuration to current format #2329

Job	Run time
build (2_12, e2e)	3m 22s
conformance	1m 33s
build (2_12, test)	11m 3s
build (2_13, e2e)	4m 6s
build (2_13, test)	12m 35s
build (3, e2e)	4m 1s
build (3, test)	8m 37s
build (2_12, examples_and_formatting)	2m 37s
build (2_13, scala3_compat_test)	7m 6s
build (3, scala3_compat_test)	9m 21s
ci-passed	1s
	1h 4m 22s

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