* improve digit_version & use it for version_checking
* more testing for digit_version
* setuptools >= 50 is needed
* fix CI
* add debuging log
* >= to ==
* fix lint
* remove
* add failure case
* replace
* fix
* consider TORCH_VERSION == 'parrots'
* add unittest
* digit_version do not deal with the case if 'parrots' in version name.
* [Enhance]: add onxx simplify
* add simple doc
* add unit test
* update docstring
* resolve some comment
* add test dependency:onnxoptimizer
* Fix onnxruntime register empty libpath
* test onnxruntime version
* set checker to false
* skip test_simplify for torch<1.5.0