Never explicitly inherit from object in Python 3-only stubs (#6777)

stdlib/csv.pyi

@@ -100,7 +100,7 @@ class DictWriter(Generic[_T]):
     def writerow(self, rowdict: Mapping[_T, Any]) -> Any: ...
     def writerows(self, rowdicts: Iterable[Mapping[_T, Any]]) -> None: ...
 
-class Sniffer(object):
+class Sniffer:
     preferred: list[str]
     def __init__(self) -> None: ...
     def sniff(self, sample: str, delimiters: str | None = ...) -> Type[Dialect]: ...