[JS] - The judge for GenkitMetrics doesn't always output in the required JSON schema when using gpt4o

[barthje]

Describe the bug
When running Evaluations where gpt4oMini is the judge the response of the judge for the GenkitMetric.ANSWER_RELEVANCY response does not follow the required JSON schema. When I switched the judge to gemini20Flash everything worked fine.
Error for the Relevancy Metric:

- answered: must be string

Provided data:

{
  "noncommittal": 0,
  "answered": 1,
  "question": "What is the wifi code?"
}

Required JSON schema:

{
  "type": "object",
  "properties": {
    "question": {
      "type": "string"
    },
    "answered": {
      "type": "string",
      "enum": [
        "0",
        "1"
      ]
    },
    "noncommittal": {
      "type": "string",
      "enum": [
        "0",
        "1"
      ]
    }
  },
  "required": [
    "question",
    "answered",
    "noncommittal"
  ],

To Reproduce
Setup of Evaluations and Metrics:

ai = genkit({
      plugins: [
        openAI({ apiKey: process.env.OPENAI_API_KEY }),
        googleAI({ apiKey: process.env.GOOGLE_API_KEY }),
        genkitEval({
          judge: gpt4oMini,
          metrics: [
            GenkitMetric.MALICIOUSNESS,
            GenkitMetric.FAITHFULNESS,
            GenkitMetric.ANSWER_RELEVANCY,
          ],
          embedder: textEmbeddingAda002,
        }),
      ],
      model: gpt4oMini,
    });

• Create a flow with an input and output
• Make sure you use a retriever
• Create a dataset with at least one input
• Run the created dataset with the flow

Expected behavior
Evaluations where all three metrics are scored correctly

Runtime (please complete the following information):

• OS: [MacOS]
• Genkit: [1.0.5]

** Node version

• v20.18.0

Additional context
Add any other context about the problem here.