Tweak actions config to use different key names in matrix #614

Job	Run time
FreeBSD-x86_64 with rust stable	1m 18s
Linux-x86_64 with rust stable	36s
Linux-aarch64 with rust stable	1m 30s
Linux-arm with rust stable	1m 27s
Linux-i686 with rust stable	1m 39s
Linux-powerpc with rust stable	1m 14s
Linux-powerpc64 with rust stable	1m 18s
Linux-powerpc64le with rust stable	1m 10s
Linux-riscv64 with rust stable	1m 14s
Linux-s390x with rust stable	1m 12s
NetBSD-x86_64 with rust stable	1m 25s
Windows-aarch64 with rust stable	2m 13s
Windows-i686 with rust stable	2m 18s
Windows-x86_64 with rust stable	3m 44s
macOS-x86_64 with rust stable	54s
macOS-aarch64 with rust stable	29s
Linux-x86_64 with rust beta	1m 31s
Linux-x86_64 with rust nightly	1m 26s
	26m 38s

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