Skip TestExtractPredictorNet if compiled without OpenCV (#42168)
Summary:
Found while trying to get RocM Caffe2 CI green
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42168
Reviewed By: seemethere
Differential Revision: D22791879
Pulled By: malfet
fbshipit-source-id: 8f7ef9711bdc5941b2836e4c8943bb95c72ef8af
