* Upgrade CI for PyTorch1.9
* fix typo
* merge build_cu101 and build_cu102 to build_cuda
* fix substitution bug
* test
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* remove redudant items
* add python 3.9 to CI
* add python 3.9 to setup.py
* remove some versions of pytorch for python 3.9 test
* fix torch version error
* delete mim files
* update ubuntu version
* fix mmcv cuda version