feat: add cargo-mutants support

[SecretSheppy]

currently only works if you manually remove the first none standard part of the json as the list of json objects is not standardized:

    {
      "scenario": "Baseline",
      "summary": "Success",
      "log_path": "log/baseline.log",
      "diff_path": null,
      "phase_results": [
        {
          "phase": "Build",
          "duration": 22.066161614,
          "process_status": "Success",
          "argv": [
            "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo",
            "test",
            "--no-run",
            "--verbose",
            "--package=hashbrown@0.17.1"
          ]
        },
        {
          "phase": "Test",
          "duration": 7.115485697,
          "process_status": "Success",
          "argv": [
            "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo",
            "test",
            "--verbose",
            "--package=hashbrown@0.17.1"
          ]
        }
      ]
    },

the problem is that the scenario field is supposed to be an object, but cargo-mutants can't stick to its own standards, and in this first fields its a string. This means that go's json package is unable to unmarshal it.