Update module.py

Author: shchur

src/gluonts/torch/model/patch_tst/module.py

@@ -108,7 +108,7 @@ def __init__(
         activation: str,
         norm_first: bool,
         num_encoder_layers: int,
-        scaling: str,
+        scaling: Optional[str],
         distr_output=StudentTOutput(),
     ) -> None:
         super().__init__()