Data augmentation seemingly not doing anything

Hello @fsalv ,

I'm curious about the random flips and rotations.

In training.py, [LL119-121](https://github.com/EscVM/RAMS/blob/bc16e52b8e2d7b5e23560e14045f13f181d03f77/utils/training.py#L120):

```python
if data_aug:
train_ds.map(random_rotate, num_parallel_calls=tf.data.experimental.AUTOTUNE)
train_ds.map(random_flip, num_parallel_calls=tf.data.experimental.AUTOTUNE)
```

I believe ``.map`` is NOT an in-place operator so I don't think this is doing anything. To check this, we can adapt the example from the Tensorflow documentation here: https://www.tensorflow.org/api_docs/python/tf/data/Dataset#map

```python
from tensorflow.data import Dataset
dataset = Dataset.range(1, 6) # ==> [ 1, 2, 3, 4, 5 ]
dataset.map(lambda x: x + 1)
list(dataset.as_numpy_iterator()) # [1, 2, 3, 4, 5] map had no effect

dataset = Dataset.range(1, 6) # ==> [ 1, 2, 3, 4, 5 ]
dataset = dataset.map(lambda x: x + 1)
list(dataset.as_numpy_iterator()) # [2, 3, 4, 5, 6] expected output
```

Does this seem like a bug to you? If so, could you please advise if you think your pretrained models were affected?