tests

Add mcl backend #223

Job	Run time
kzg_ci	43s
backend_ci (ubuntu-latest, blst)	16m 13s
backend_ci (ubuntu-latest, zkcrypto)	32m 50s
backend_ci (ubuntu-latest, arkworks5)	19m 7s
backend_ci (ubuntu-latest, arkworks4)	19m 38s
backend_ci (ubuntu-latest, arkworks3)	17m 34s
backend_ci (ubuntu-latest, constantine)	26m 14s
backend_ci (ubuntu-latest, mcl)	5m 7s
backend_ci (windows-latest, blst)	5m 45s
backend_ci (windows-latest, zkcrypto)	9m 20s
backend_ci (windows-latest, arkworks5)	7m 3s
backend_ci (windows-latest, arkworks4)	6m 38s
backend_ci (windows-latest, arkworks3)	5m 44s
backend_ci (windows-latest, constantine)	10m 35s
backend_ci (windows-latest, mcl)	3m 10s
backend_ci (macos-latest, blst)	6m 15s
backend_ci (macos-latest, zkcrypto)	9m 22s
backend_ci (macos-latest, arkworks5)	6m 41s
backend_ci (macos-latest, arkworks4)	6m 26s
backend_ci (macos-latest, arkworks3)	7m 1s
backend_ci (macos-latest, constantine)	13m 0s
backend_ci (macos-latest, mcl)	7m 1s
	4h 1m 27s

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