Field class has 255 and 254 values in the segmentations

Until now this went unnoticed as we divided the values in YOEO by 127 and casted them to an int, so this was not an issue.
But @jaagut originally noticed the issue and created https://github.com/bit-bots/TORSO_21_dataset/blob/master/scripts/fix_segmentations.py but It somehow got not applied.