fix complaint

Signed-off-by: M Q <mingmelvinq@nvidia.com>

Author: MMelQin

monai/deploy/core/app_context.py

@@ -47,7 +47,9 @@ def update(self, args: Dict[str, str]):
             self._model_loaded = False  # path changed, reset the flag to re-load
 
         if not self._model_loaded:
-            self.models = ModelFactory.create(abspath(self.model_path)) if not self._model_loaded else self.models
+            self.models: Optional[Model] = (
+                ModelFactory.create(abspath(self.model_path)) if not self._model_loaded else self.models
+            )
             self._model_loaded = True
 
     def __repr__(self):