Remove duplicate line (pytorch#91006)

Two [nearly](pytorch#90927) [identical](pytorch#90948) PRs both got merged without a reported merge conflicts? First time for everything
Pull Request resolved: pytorch#91006
Approved by: https://github.com/kit1980

CONTRIBUTING.md

@@ -92,8 +92,6 @@ To develop PyTorch on your machine, here are some tips:
 ### Instructions
 _**Note**: If you get stuck at any step, check out the [tips and debugging](#tips-and-debugging) section below for common solutions_
 
-_**Note**: If you get stuck at any step, check out the [tips and debugging](#tips-and-debugging) section below for common solutions_
-
 1. Uninstall all existing PyTorch installs. You may need to run `pip
 uninstall torch` multiple times. You'll know `torch` is fully
 uninstalled when you see `WARNING: Skipping torch as it is not