chore: fix some clippy warnings (#69) #56

Job	Run time
clippy_check_blst	4m 21s
clippy_check_pairing	4m 20s
Checking fmt and docs	26s
set-msrv	4s
windows (x86_64-pc-windows-msvc, stable)	3m 30s
macos (1.63.0)	8m 14s
macos (stable)	1m 45s
linux (i686-unknown-linux-gnu, 1.63.0, sudo apt update && sudo apt install gcc-multilib)	9m 50s
linux (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	4m 10s
linux (x86_64-unknown-linux-gnu, 1.63.0)	5m 59s
linux (x86_64-unknown-linux-gnu, stable)	2m 11s
	44m 50s

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