Update validate_binaries.sh

Author: atalman

.github/scripts/validate_binaries.sh

@@ -63,7 +63,7 @@ conda run -n build_binary pip install fbgemm-gpu --index-url "$PYTORCH_URL"
 conda run -n build_binary pip install torchmetrics==1.0.3
 
 # install torchrec
-conda run -n build_binary pip install torchrec --index-url "$PYTORCH_URL"
+conda run -n build_binary pip install torchrec --extra-index-url "$PYTORCH_URL"
 
 # Run small import test
 conda run -n build_binary python -c "import torch; import fbgemm_gpu; import torchrec"