feat: bump gnark version to 0.12

[Mechanix97]

Bump gnark version from 0.10 to 0.12

Description

Update the version in go.mod and go.sum. Update the test files of groth16 to make it work (plonk 0.10 test files still works). fix the CI to use the correct test files. Update the docs.

Type of change

• [ ] New feature

Checklist

• [ ] “Hotfix” to testnet, everything else to staging
• [ ] Linked to Github Issue
• [ ] This change depends on code or research by an external entity
  • [ ] Acknowledgements were updated to give credit
• [ ] Unit tests added
• [ ] This change requires new documentation.
  • [ ] Documentation has been added/updated.
• [ ] This change is an Optimization
  • [ ] Benchmarks added/run
• [ ] Has a known issue
  • Link to the open issue addressing it
• [ ] If your PR changes the Operator compatibility (Ex: Upgrade prover versions)
  • [ ] This PR adds compatibility for operator for both versions and do not change batcher/docs/examples
  • [ ] This PR updates batcher and docs/examples to the newer version. This requires the operator are already updated to be compatible