[tmva][sofie] Fix Keras BinaryOp test model shapes and improve reproducibility

[Shlok-Saxena]

This Pull request

Fixes a shape mismatch in the Keras test model generator used for SOFIE tests and improves reproducibility of generated models.

Changes or fixes:

• Fixed incorrect training input/target tensor shapes in generateBinaryOpModel() from (2,1) to (2,2) to match the model input signature Input(shape=(2,))
• Added tf.keras.utils.set_random_seed(0) so model initialization and generated outputs are reproducible across runs, improving stability of SOFIE Keras parser tests.

Checklist:

• tested changes locally
• updated the docs (if necessary)