[JIT] nvfuser test - use only major & minor versions
torch.version.cuda.split('.') can have 2 or 3 elements depending on whether the version string contains a patch number. This updates the test so it doesn't error out when the version has > 2 parts.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75706
Approved by: https://github.com/ngimel
