Prepare MLflow experiment and log params

def on_train_begin(self, **kwargs: Any) -> None:
        "Prepare MLflow experiment and log params"
        self.client = mlflow.tracking.MlflowClient(self.uri)
        exp = self.client.get_experiment_by_name(self.exp_name)
        self.exp_id = self.client.create_experiment(self.exp_name) if exp is None else exp.experiment_id
        run = self.client.create_run(experiment_id=self.exp_id)
        self.run = run.info.run_uuid
        for k,v in self.params.items():
            self.client.log_param(run_id=self.run, key=k, value=v)