[BUG] - TorchRL PPO tutorial uses deprecated CUDA check

[mikemykhaylov]

Add Link

https://pytorch.org/tutorials/intermediate/reinforcement_ppo.html

Describe the bug

Running the code in Colab yields the following deprecation warning during the CUDA check:

<ipython-input-4-1b523198624f>:1: UserWarning: 'has_cuda' is deprecated, please use 'torch.backends.cuda.is_built()'
  device = "cpu" if not torch.has_cuda else "cuda:0"

Describe your environment

• Platform: Google Colab
• CUDA: yes, Tesla T4
• Pytorch version: 2.1