Remove pin on libuv from instructions (pytorch#159504)

This package doesn't exist at conda-forge and causes some confusion for users.
see https://anaconda.org/conda-forge/libuv/files?version=1.39.0

libuv is quite stable, so the newer versions should be fine. we build with them anyway at conda-forge.

see: conda-forge/libuv-feedstock#80

Hopefully this can help future users.

Fixes conda-forge/libuv-feedstock#80

Pull Request resolved: pytorch#159504
Approved by: https://github.com/seemethere

Author: hmaarrfk

README.md

@@ -276,7 +276,7 @@ conda install pkg-config libuv
 pip install mkl-static mkl-include
 # Add these packages if torch.distributed is needed.
 # Distributed package support on Windows is a prototype feature and is subject to changes.
-conda install -c conda-forge libuv=1.39
+conda install -c conda-forge libuv
 ```
 
 #### Install PyTorch