tests

Optionally disable c bindings #197

Job	Run time
kzg_ci	48s
backend_ci (ubuntu-latest, blst)	14m 44s
backend_ci (ubuntu-latest, zkcrypto)	31m 26s
backend_ci (ubuntu-latest, arkworks)	20m 20s
backend_ci (ubuntu-latest, arkworks3)	17m 20s
backend_ci (ubuntu-latest, constantine)	24m 37s
backend_ci (windows-latest, blst)	4m 36s
backend_ci (windows-latest, zkcrypto)	8m 49s
backend_ci (windows-latest, arkworks)	5m 36s
backend_ci (windows-latest, arkworks3)	5m 34s
backend_ci (windows-latest, constantine)	7m 12s
backend_ci (macos-latest, blst)	5m 43s
backend_ci (macos-latest, zkcrypto)	11m 0s
backend_ci (macos-latest, arkworks)	6m 7s
backend_ci (macos-latest, arkworks3)	6m 51s
backend_ci (macos-latest, constantine)	9m 5s
	2h 59m 48s

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