bump version to 1.0 (pytorch#11717)

Summary:
I'm just doing the honors and bumping the version to 1.0.0.

1.0 preview and RC releases will have the 1.0.0.dev{date} tag
Pull Request resolved: pytorch#11717

Reviewed By: SsnL

Differential Revision: D9840857

Pulled By: soumith

fbshipit-source-id: 4c9c2e01dccb3c521dab26c49e1569d970a87ace

Author: soumith

setup.py

@@ -283,7 +283,7 @@ def patched_link(self, *args, **kwargs):
 # Version, create_version_file, and package_name
 ################################################################################
 package_name = os.getenv('TORCH_PACKAGE_NAME', 'torch')
-version = '0.5.0a0'
+version = '1.0.0a0'
 if os.getenv('PYTORCH_BUILD_VERSION'):
     assert os.getenv('PYTORCH_BUILD_NUMBER') is not None
     build_number = int(os.getenv('PYTORCH_BUILD_NUMBER'))