Update README.md to mention 2.8 release (#9560)

Author: bhavya01

README.md

@@ -32,7 +32,7 @@ Note: Builds are available for Python 3.8 to 3.11; please use one of the support
 # - for conda
 # conda create -n py311 python=3.11
 
-pip install torch==2.7.0 'torch_xla[tpu]==2.7.0'
+pip install torch==2.8.0 'torch_xla[tpu]==2.8.0'
 
 # Optional: if you're using custom kernels, install pallas dependencies
 pip install 'torch_xla[pallas]'