Make CI work with both Circom1 and Circom2

[Georgios Konstantopoulos]

re tests in ci: many tests are now failing (cargo test --features circom-2), because it tries to call the circom1 wasm with the circom2 features. I guess once the feature is less experimental, one could remove the feature flag and instead detect the version of the wasm by calling getVersion() and change the code path accordingly.

Originally posted by @philsippl in #14 (comment)