Linting fix

Author: GavinZZ

samtranslator/model/__init__.py

@@ -330,7 +330,7 @@ def validate_properties_and_return_model(self, cls: Type[RT]) -> RT:
         try:
             return cls.parse_obj(self._generate_resource_dict()["Properties"])
         except ValidationError as e:
-            error_properties = ""
+            error_properties: str = ""
             with suppress(KeyError):
                 error_properties = ", ".join([error["loc"][0] for error in e.errors()])
             raise InvalidResourceException(