Fix/error in accuracy tests for ner task

[chakravarthik27]

update the calculate_f1_score function in /langtest\utils\util_metrics.py

    if isinstance(y_true, list) and isinstance(y_pred, list):
        unique_labels = set(y_true + y_pred)
    elif isinstance(y_true, pd.Series) and isinstance(y_pred, pd.Series):
        unique_labels = set(y_true.tolist() + y_pred.tolist())
    else:
        raise ValueError(
            "y_true and y_pred must be of the same type. Supported types are list and pandas Series."
        )