Remove unnecessary index (rapidsai#1820)

Addresses rapidsai#1808 (comment)

Authors:
  - Vyas Ramasubramani (https://github.com/vyasr)

Approvers:
  - Bradley Dice (https://github.com/bdice)
  - James Lamb (https://github.com/jameslamb)

URL: rapidsai#1820

dependencies.yaml

@@ -367,6 +367,4 @@ dependencies:
       - output_types: requirements
         packages:
           # pip recognizes the index as a global option for the requirements.txt file
-          # This index is needed for rapids_logger
-          - --extra-index-url=https://pypi.nvidia.com
           - --extra-index-url=https://pypi.anaconda.org/rapidsai-wheels-nightly/simple