Update CUDA versions in Github (#3296)

Summary:
Pull Request resolved: #3296

CUDA versions need to be updated as 11.8 is not supported any more.

Created from CodeHub with https://fburl.com/edit-in-codehub

Reviewed By: TroyGarden

Differential Revision: D80532663

fbshipit-source-id: 18bbfa3c1be426541a068e9823758c1cdb6c252d

Author: kausv

README.MD

@@ -48,9 +48,9 @@ Check out the [Getting Started](https://pytorch.org/torchrec/setup-torchrec.html
 
    pip install torch --index-url https://download.pytorch.org/whl/nightly/cu126
 
-   CUDA 11.8
+   CUDA 12.9
 
-   pip install torch --index-url https://download.pytorch.org/whl/nightly/cu118
+   pip install torch --index-url https://download.pytorch.org/whl/nightly/cu129
 
    CPU
 
@@ -73,9 +73,9 @@ Check out the [Getting Started](https://pytorch.org/torchrec/setup-torchrec.html
 
    pip install fbgemm-gpu --index-url https://download.pytorch.org/whl/nightly/cu126
 
-   CUDA 11.8
+   CUDA 12.9
 
-   pip install fbgemm-gpu --index-url https://download.pytorch.org/whl/nightly/cu118
+   pip install fbgemm-gpu --index-url https://download.pytorch.org/whl/nightly/cu129
 
    CPU