ci: more concurrency groups #1026

Job	Run time
build (nightly) / rust	17s
build (msrv) / rust	18s
build (stable) / rust	12s
style (stable) / rust	13s
build no_std (stable) / rust	17s
build no_std (stable) [Windows] / rust	1m 8s
build no_std (stable) [w/o builder] / rust	17s
build no_std (nightly) / rust	18s
tests with miri (nightly) / rust	1m 25s
style (nightly) / rust	21s
build no_std (msrv) / rust	25s
style (msrv) / rust	24s
	5m 35s

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