Improve root calculation for KZG setup() #748

Job	Run time
Bitrot check	7m 13s
Rustfmt	21s
Build target wasm32-unknown-unknown	4m 6s
Intra-doc links	3m 41s
Build target wasm32-wasi	3m 53s
Test on ubuntu-latest with basic features	11m 54s
Test on windows-latest with basic features	18m 20s
Test on macOS-latest with basic features	14m 8s
Test on ubuntu-latest with all features	18m 10s
Test on windows-latest with all features	22m 30s
Test on macOS-latest with all features	15m 46s
	2h 0m 2s

Provide feedback