Add musl build action #17

Job	Run time
Build x86_64-pc-windows-msvc	2m 55s
Build aarch64-unknown-linux-musl	2m 13s
Build i686-pc-windows-msvc	3m 8s
Build x86_64-unknown-linux-gnu	2m 33s
Build armv7-unknown-linux-gnueabihf	2m 38s
Build i686-unknown-linux-gnu	2m 42s
Build x86_64-unknown-linux-musl	2m 9s
Build macOS universal binary	1m 48s
Build aarch64-unknown-linux-gnu	2m 42s
	22m 48s

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