Prepare for 1.6.0-M3 release #897

Job	Run time
test (ubuntu-latest, stable)	1m 9s
bindings-windows (x86_64-pc-windows-msvc, true)	53s
bindings-windows (i686-pc-windows-msvc, false)	54s
features (--no-default-features)	1m 10s
test (ubuntu-latest, beta)	1m 9s
bindings-macos (x86_64-apple-darwin)	1m 11s
features (--no-default-features --features serialization)	1m 10s
test (windows-latest, stable)	52s
features (--no-default-features --features serial)	1m 10s
documentation	1m 10s
features (--no-default-features --features tls)	1m 8s
conformance	1m 10s
bindings-linux (x86_64-unknown-linux-gnu)	1m 7s
test (windows-latest, beta)	52s
bindings-linux (i686-unknown-linux-gnu)	1m 9s
bindings-linux (x86_64-unknown-linux-musl)	1m 7s
guide	1m 1s
bindings-linux (arm-unknown-linux-gnueabihf)	1m 7s
bindings-linux (arm-unknown-linux-musleabihf)	1m 7s
linting (stable)	54s
bindings-linux (aarch64-unknown-linux-gnu)	1m 9s
linting (beta)	54s
bindings-linux (aarch64-unknown-linux-musl)	1m 8s
bindings-linux (armv7-unknown-linux-gnueabihf)	1m 7s
bindings-linux (arm-unknown-linux-gnueabi)	1m 6s
packaging	1s
release	1s
	26m 56s

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