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

stdlib/bz2.pyi

@@ -128,13 +128,13 @@ class BZ2File(BaseStream, IO[bytes]):
     def writelines(self, seq: Iterable[ReadableBuffer]) -> None: ...
 
 @final
-class BZ2Compressor(object):
+class BZ2Compressor:
     def __init__(self, compresslevel: int = ...) -> None: ...
     def compress(self, __data: bytes) -> bytes: ...
     def flush(self) -> bytes: ...
 
 @final
-class BZ2Decompressor(object):
+class BZ2Decompressor:
     def decompress(self, data: bytes, max_length: int = ...) -> bytes: ...
     @property
     def eof(self) -> bool: ...