Get rid of the `getrandom` and `OsRng` requirement #153

Job	Run time
doc	16s
clippy	20s
no_std (1.75.0, armv7a-none-eabi)	30s
cross (powerpc-unknown-linux-gnu, 1.75.0)	1m 2s
no_std (1.75.0, thumbv7em-none-eabi)	32s
rustfmt	7s
cross (powerpc-unknown-linux-gnu, stable)	49s
test (1.75.0)	34s
no_std (1.75.0, wasm32-unknown-unknown)	31s
test (stable)	43s
no_std (stable, armv7a-none-eabi)	27s
no_std (stable, thumbv7em-none-eabi)	32s
no_std (stable, wasm32-unknown-unknown)	24s
	6m 47s

Provide feedback