Adding min_delta setting for early stopping in training settings

[elloza]

It is just a new parameter for the training settings to define a minimum value to be considered as an improvement in the evaluation metric.

Maybe it can be useful. It is available in frameworks like Keras and PyTorch.

Greetings and congratulations for your work.

[Ethan-TZ]

@elloza Thanks for your contribution! I will check it soon.