sha2

Bump MSRV to 1.81 (#631) #1245

Job	Run time
riscv32-zknh	1m 26s
riscv64-zknh	1m 34s
set-msrv / set-msrv	2s
minimal-versions / minimal-versions	45s
build (1.81.0, thumbv7em-none-eabi)	29s
build (1.81.0, wasm32-unknown-unknown)	23s
linux (i686-unknown-linux-gnu, 1.81.0, sudo apt update && sudo apt install gcc-multilib)	59s
build (1.81.0, loongarch64-unknown-linux-gnu)	21s
build (stable, thumbv7em-none-eabi)	15s
linux (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	47s
build (stable, wasm32-unknown-unknown)	18s
linux (x86_64-unknown-linux-gnu, 1.81.0)	42s
build (stable, loongarch64-unknown-linux-gnu)	15s
cross (1.81.0, aarch64-unknown-linux-gnu, default)	40s
cross (1.81.0, powerpc-unknown-linux-gnu, default)	44s
linux (x86_64-unknown-linux-gnu, stable)	40s
cross (stable, aarch64-unknown-linux-gnu, default)	36s
macos (1.81.0)	36s
cross (stable, powerpc-unknown-linux-gnu, default)	43s
macos (stable)	24s
wasm (1.81.0, -C target-feature=-simd128)	1m 1s
wasm (stable, -C target-feature=-simd128)	51s
wasm (1.81.0, -C target-feature=+simd128)	34s
wasm (stable, -C target-feature=+simd128)	31s
windows (1.81.0, x86_64-pc-windows-gnu)	1m 6s
windows (stable, x86_64-pc-windows-gnu)	2m 49s
	19m 31s

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