change the default pip

Author: HumphreyYang

lectures/kesten_processes.md

@@ -45,10 +45,9 @@ tags: [hide-output]
 ---
 !pip install quantecon
 !pip install --upgrade yfinance
-
-!pip install --upgrade "jax[cuda]" -f https://storage.googleapis.com/jax-releases/jax_cuda_releases.html
-# If you do not have CUDA support on your machine, run the line below instead:
-# !pip install --upgrade "jax[CPU]"
+# If your machine has CUDA support, please follow the guide in GPU Warning. 
+# Otherwise, run the line below:
+!pip install --upgrade "jax[CPU]"
 ```
 
 ## Overview