fix command line flags.

ml-agents/tests/yamato/standalone_build_tests.py

 from .yamato_utils import get_base_path, run_standalone_build
 
 
-def main(scene_path, build_target):
+def main(scene_path, build_target, mlagents_scripting_backend):
     base_path = get_base_path()
     print(f"Running in base path {base_path}")
 
         output_path=executable_name,
         scene_path=scene_path,
         build_target=build_target,
+        scripting_backend=mlagents_scripting_backend,
         log_output_path=None,  # Log to stdout so we get timestamps on the logs
     )
 
         "--build-target", default="mac", choices=["mac", "linux", "ios", "webgl"]
     )
     parser.add_argument(
-        "--scripting-backen", default="mono", choices=["mono", "il2cpp"]
+        "--mlagents-scripting-backend", default="mono", choices=["mono", "il2cpp"]
-    main(args.scene, args.build_target)
+    main(args.scene, args.build_target, args.mlagents_scripting_backend)