reduce amount of CI builds #60

Job	Run time
macos-x86_64	3m 33s
linux (x86_64-unknown-linux-gnu)	3m 29s
macos-universal	6m 27s
linux (i686-unknown-linux-gnu)	4m 39s
linux-cross (aarch64-unknown-linux-gnu, aarch64, -e JEMALLOC_SYS_WITH_LG_PAGE=16)	3m 30s
linux-cross (armv7-unknown-linux-gnueabihf, armv7)	3m 35s
musllinux (x86_64-unknown-linux-musl)	3m 16s
musllinux (i686-unknown-linux-musl)	3m 15s
linux-cross (s390x-unknown-linux-gnu, s390x)	3m 40s
musllinux-cross (aarch64-unknown-linux-musl, aarch64, -e JEMALLOC_SYS_WITH_LG_PAGE=16)	3m 19s
windows (x86_64-pc-windows-msvc, x64)	10m 56s
linux-cross (powerpc64le-unknown-linux-gnu, ppc64le)	3m 33s
musllinux-cross (armv7-unknown-linux-musleabihf, armv7)	3m 17s
windows (i686-pc-windows-msvc, x86)	10m 55s
linux-cross (powerpc64-unknown-linux-gnu, ppc64)	3m 47s
windows (aarch64-pc-windows-msvc, x64)	10m 55s
Release	10s
	1h 22m 16s

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