bump version `1.6.0` (#247) #167

Job	Run time
x86_64-linux-musl	1m 45s
i686-linux-musl	1m 35s
aarch64-linux-musl	1m 31s
x86_64-apple-darwin14	1m 42s
aarch64-apple-darwin14	1m 34s
x86_64-w64-mingw32	1m 45s
i686-w32-mingw32	1m 50s
Create a Universal macOS binary	11s
Create Github Release	10s
	12m 3s

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