Fix llama runner mac CI jobs (#2903)

Summary:
In MacOS python will go look for `DYLD_LIBRARY_PATH` instead of `LD_LIBRARY_PATH` so add that fixes the CI failures.

Pull Request resolved: #2903

Reviewed By: mergennachin, Jack-Khuu, GregoryComer

Differential Revision: D55833147

Pulled By: larryliu0820

fbshipit-source-id: a28d58917d7e934d340237a04cb82079cf3f81d1

Author: larryliu0820

.ci/scripts/test_llama.sh

@@ -139,6 +139,7 @@ if [[ "${MODE}" == "xnnpack+kv+custom" ]]; then
 fi
 # Add dynamically linked library location
 export LD_LIBRARY_PATH=${PWD}/cmake-out/lib
+export DYLD_LIBRARY_PATH=${PWD}/cmake-out/lib
 $PYTHON_EXECUTABLE -m examples.models.llama2.export_llama ${EXPORT_ARGS}
 
 # Create tokenizer.bin.