[fix] failing PLC comparetest due to incorrect ref filename

    if test_info.config.option.create_cut:

        # CUT creation mode will run a comparison with REF

        out_file_ref = str(OUTPUT_PATH_REF.joinpath(out_file_stem))

        if plc_error_pattern:

            out_file_ref = out_file_ref.with_stem(

                f"{out_file_ref.stem}_plc_{plc_error_pattern.stem}"

            )

        try:

            ref, ref_fs = readfile(out_file_ref)