fix for invalid GPU error caused by (test/test_net_speed.py::TestConvSpeed::test_mnist) when testing in CI (#31)

* install the pytorch cpu only version

* get rid of torch gpu version

* test passed seems to get rid of invalid gpu error

* added the libs to requirements.txt

* lol

requirements.txt

@@ -2,6 +2,8 @@ numpy
 # util deps
 requests
 # testing deps
-torch
+--find-links https://download.pytorch.org/whl/torch_stable.html
+torch==1.6.0+cpu
+torchvision==0.7.0+cpu
 pytest
 tqdm