adding scikit-build for sphinx builder

requirements.txt

@@ -1,18 +1,19 @@
 foolbox
 scipy>=1.1.0
 numpy>=1.14.2
+cython>=0.28.5
 torch>=1.5.1
 torchvision>=0.6.1
 tqdm>=4.19.9
 setuptools>=39.0.1
 matplotlib>=2.1.0
 gym>=0.10.4
+scikit-build>=0.11.0
 scikit_image>=0.13.1
 scikit_learn>=0.19.1
 opencv-python>=3.4.0.12
 sphinx_rtd_theme>=0.4.1
 pytest>=3.4.0
-cython>=0.28.5
 pandas>=0.23.4
 tensorboardX>=1.7
 pre-commit