[Bugfix] Path join when building local path for S3 clone (#12353)

Signed-off-by: Omer Dayan (SW-GPU) <omer@run.ai>

vllm/transformers_utils/s3_utils.py

@@ -145,7 +145,8 @@ def pull_files(self,
             return
 
         for file in files:
-            destination_file = self.dir + file.removeprefix(base_dir)
+            destination_file = os.path.join(self.dir,
+                                            file.removeprefix(base_dir))
             local_dir = Path(destination_file).parent
             os.makedirs(local_dir, exist_ok=True)
             self.s3.download_file(bucket_name, file, destination_file)