Fix deprecated PyTorch calls in optimizers and module

[VelizarZ]

I encountered issues running the experiments with Python 3.12 using the existing installation instructions targeting Python >=3.7. Specifically:

-Minor bugs in experiments/optimizers_L1L2.py caused warnings and deprecated usage errors.

-The training process for mnist_rot dataset failed due to the absence of .copy() in experiments/datasets/mnist_rot/own_transforms.py.