Add entry for torch/lib/pythonX.Y in .gitignore (pytorch#11083)

Summary:
I've had `torch/lib/python3.6` show up as part of the build for some time now. It's not ignored which means I need to be extra careful about checking in files, or I end up with a thousand of them in my index.
Pull Request resolved: pytorch#11083

Differential Revision: D9580453

Pulled By: apaszke

fbshipit-source-id: 369e4fe87962696532d111b24f2a4a99b9572bf2

.gitignore

@@ -64,6 +64,7 @@ torch/lib/pkgconfig
 torch/lib/protoc
 torch/lib/tmp_install
 torch/lib/torch_shm_manager
+torch/lib/python*
 torch/version.py
 
 # IPython notebook checkpoints