Add nvidia channel for cudatoolkit (#1402)

Summary:
nvidia channel is required for installing cudatoolkit

Pull Request resolved: https://github.com/facebookresearch/pytorch3d/pull/1402

Reviewed By: davidsonic

Differential Revision: D42208583

Pulled By: bottler

fbshipit-source-id: 83d0e63efcf7772b778ca909fd9b14d28829c5b6

INSTALL.md

@@ -21,7 +21,7 @@ The runtime dependencies can be installed by running:
 ```
 conda create -n pytorch3d python=3.9
 conda activate pytorch3d
-conda install -c pytorch pytorch=1.9.1 torchvision cudatoolkit=11.6
+conda install pytorch=1.13.0 torchvision pytorch-cuda=11.6 -c pytorch -c nvidia
 conda install -c fvcore -c iopath -c conda-forge fvcore iopath
 ```