Improve Validation Logic for Dropout Fraction in DropoutMixin

[ram-from-tvl]

Pull Request

Description

This PR improves the validation logic for the dropout_fraction field in the DropoutMixin class. The current implementation allows dropout_fraction to accept both a float and a list[float], which introduces ambiguity and complexity in validation.
The updated logic ensures:

• If dropout_fraction is a float, dropout_timedeltas_minutes must be empty.
• If dropout_fraction is a list[float], its length must match the length of dropout_timedeltas_minutes.
  Let me know if you need further improvements!

[ram-from-tvl]

Hi @peterdudfield
I was exploring the repo and found it really interesting. I’ve been learning its inner workings and wanted to check if this PR is helpful. Let me know if any improvements are needed!
Thankyou!

[peterdudfield]

Please see lint errors

I think in general this will be useful

[ram-from-tvl]

Please see lint errors

I think in general this will be useful

@peterdudfield
I have solved some of the lint issues. Hope this is good to go.
Thankyou!