GPUs != Neuron Devices (when it comes to instance selector)

[dims]

ec2-instance-selector has a totally different option for Neuron Devices ( https://github.com/search?q=repo%3Aaws%2Famazon-ec2-instance-selector+accelerators&type=code ).

So the gpus field in instanceSelector does NOT cover Neuron Devices. For example if you say gpus: 0 you may still get an instance type with a neuron device/accelerator.

To explicitly specify the number of neuron devices you need to add another field neuron_devices for example see:

    instanceSelector:
      vCPUs: 8
      gpus: 0
      neuron_devices: 0
      memory: 16GiB
      cpuArchitecture: x86_64

There was a bug in ec2-instance-selector as well in the accelerator selection, which has been fixed and picked up in this PR

[dims]

we also need aws/amazon-ec2-instance-selector#414

[dims]

related to #7897