bump pytorch minimum constraint to 1.1.0

Author: soumith

setup.py

@@ -62,7 +62,7 @@ def write_version_file():
 
 readme = open('README.rst').read()
 
-pytorch_package_name = os.getenv('TORCHVISION_PYTORCH_DEPENDENCY_NAME', 'torch')
+pytorch_package_name = os.getenv('TORCHVISION_PYTORCH_DEPENDENCY_NAME', 'torch >= 1.1.0')
 
 requirements = [
     'numpy',