Crash when setting `LearningRateSchedule` for training Keras model on TMVA

[mrzimu]

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Describe the bug

When booking TMVA.Types.kPyKeras method, once add LearningRateSchedule option to the option string, a FATAL error will occure.

Expected behavior

Just fix it? Make it work? Or something like these...

To Reproduce

Add LearningRateSchedule option to line 65, /tutorials/tmva/keras/ClassificationKeras.py:

factory.BookMethod(dataloader, TMVA.Types.kPyKeras, 'PyKeras',
                   H:!V:VarTransform=D,G:FilenameModel=model.h5:NumEpochs=20:BatchSize=32:LearningRateSchedule=10,0.01;20,0.005')

Setup

1. ROOT version: 6.24.06
2. Operating system: Ubuntu20.04
3. Obtain way: binary download

Additional context