title: get warnings.warn('User provided device_type of \'cuda\', but CUDA is not available. Disabling') while train yolov5 model
body: <p>I am trying to train yolov5 model with colab
  with this code : <a href="https://colab.research.google.com/drive/17o6Ci-x8hIMhWXXzxRQcxvB5MfvjEeDV?usp=sharing" rel="nofollow noreferrer">https://colab.research.google.com/drive/17o6Ci-x8hIMhWXXzxRQcxvB5MfvjEeDV?usp=sharing</a></p>
  <pre><code>`!python train.py --img 415 --batch 16 --epochs 30 --data dataset.yaml --device cpu --weights yolov5s.pt --cache`
  </code></pre>
  <p>I mention --device cpu but also I get same message
  <code>warnings.warn('User provided device_type of \'cuda\', but CUDA is not available. Disabling')</code></p>