[CI/Build] fix pre-compiled wheel install for exact tag (#11373)

Signed-off-by: Daniele Trifirò <dtrifiro@redhat.com>

setup.py

@@ -466,7 +466,7 @@ def get_vllm_version() -> str:
             version += f"{sep}empty"
     elif _is_cuda():
         if envs.VLLM_USE_PRECOMPILED:
-            version += ".precompiled"
+            version += f"{sep}precompiled"
         else:
             cuda_version = str(get_nvcc_cuda_version())
             if cuda_version != MAIN_CUDA_VERSION: