async isValidChatCompletionModel(modelName = "") {
    const models = await this.fetchModels(process.env.GEMINI_API_KEY);
    return models.some((model) => model.id === modelName);
  }
Checks if a model is valid for chat completion (unused)
@deprecated
@param {string} modelName - The name of the model to check
@returns {Promise<boolean>} A promise that resolves to a boolean indicating if the model is valid