Updated the gpu playbook
Major updates:
- Use nvidia-driver-assistant to decide which driver package to install, cuda-drivers (older GPU models) or nvidia-open (newer GPU models)
- In group_vars/all, configure "nvidia_version: " without any value. This allows ansible to install the latest version of the drivers by default. The current latest version is 570.
- To install a specific version on a node, add the version as a host var, e.g. nvidia_version: "550"