Avoid string comparisons for PyTorch version comparison

[fmassa]

🚀 Feature

PyTorch now exposes torch.__version__ as a TorchVersion object, which allows for better version comparisons.
We might be able to simplify things like https://github.com/pytorch/vision/pull/4285/files#r692734821

[oke-aditya]

I can probably dig into this once I get time.

[nivedwho]

The new method you suggested only works from 1.10.0 torch version right? In that case would it make sense to use it here, since earlier versions would throw an error? I am new to this library so please correct me if I am wrong.

[fmassa]

@nivedwho modifying this in torchvision would be fine as latest torchvision depends on latest PyTorch. For projects that depend on both torchvision and PyTorch and are pinned to an older version, TorchVersion might not be available so another solutions (specific to those projects) would need to be used.

[nivedwho]

@fmassa Got it! I worked on this and found that comparison operations other than > are currently not working for TorchVersion so I made a PR to PyTorch to solve this issue - pytorch/pytorch#63848 .
Once this gets merged we can use TorchVersion to solve this particular issue, since >= operation is used here.