fix: Include Optional in parameter type and remove Union

docs/pt/docs/deployment/docker.md

@@ -161,7 +161,7 @@ def read_root():
 
 
 @app.get("/items/{item_id}")
-def read_item(item_id: int, q: Union[str, None] = None):
+def read_item(item_id: int, q: Optional[str] = None):
     return {"item_id": item_id, "q": q}
 ```