[CI/Build] make pip install vllm work in macos (for import only) (vllm-project#8118)

Author: tomeras91

setup.py

@@ -362,7 +362,8 @@ def get_vllm_version() -> str:
     version = find_version(get_path("vllm", "version.py"))
 
     if _no_device():
-        version += "+empty"
+        if envs.VLLM_TARGET_DEVICE == "empty":
+            version += "+empty"
     elif _is_cuda():
         cuda_version = str(get_nvcc_cuda_version())
         if cuda_version != MAIN_CUDA_VERSION: