Change zk backend to bellperson + blstrs #614

Job	Run time
Build target wasm32-wasi	55s
Bitrot check	1m 3s
Test on windows-latest	5m 38s
Build target wasm32-unknown-unknown	51s
Test on ubuntu-latest	3m 10s
Test on macOS-latest	3m 26s
Lint	1m 13s
Rustfmt	13s
Nightly lint	18s
Security - Cargo Audit	3m 18s
Intra-doc links	1m 22s
	21m 27s

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