parser / properties / LazyReferencePropertyProxy: enforce nullable to false

  - Having nullable to `true` lead to invalid source generation
    Since `LazyReferencePropertyProxy` is only made to be used
    for inner property reference, it seems unamrfull
    It's ~nullability shall be define on its parent

Author: Nementon

openapi_python_client/parser/properties/__init__.py

@@ -78,7 +78,7 @@ def __deepcopy__(self, memo: Any) -> Property:
 
     def __getattr__(self, name: str) -> Any:
         if name == "nullable":
-            return not self._required
+            return False
         elif name == "required":
             return self._required
         else: