Bump `crypto-bigint` to 0.6.0-pre.5 #120

Job	Run time
build-benchmarks	2m 40s
clippy	2m 19s
build-wasm (1.73.0, wasm32-unknown-unknown)	16s
codecov	46s
build-wasm (stable, wasm32-unknown-unknown)	18s
rustfmt	11s
slow-tests (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	2m 31s
tests (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	1m 23s
slow-tests (x86_64-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	3m 11s
tests (x86_64-unknown-linux-gnu, stable)	41s
	14m 16s

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