std feature flag #23

Job	Run time
Docs	19s
Test	25s
build_versions (stable)	2m 34s
cargo-deny (aarch64-apple-ios)	15s
build_versions (beta)	2m 31s
Lint	19s
cargo-deny (aarch64-linux-android)	16s
build_versions (1.67.0)	3m 19s
cargo-deny (i686-pc-windows-gnu)	18s
cargo-deny (i686-pc-windows-msvc)	19s
cargo-deny (i686-unknown-linux-gnu)	16s
cargo-deny (wasm32-unknown-unknown)	15s
cargo-deny (x86_64-apple-darwin)	17s
cargo-deny (x86_64-apple-ios)	16s
cargo-deny (x86_64-pc-windows-gnu)	16s
cargo-deny (x86_64-pc-windows-msvc)	16s
cargo-deny (x86_64-unknown-linux-gnu)	17s
cargo-deny (x86_64-unknown-redox)	16s
	12m 44s

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