Apply ruff/Pylint rule PLR1711

PLR1711 Useless `return` statement at end of function

Author: DimitriPapadopoulos

src/zarr/abc/store.py

@@ -284,7 +284,6 @@ async def _set_many(self, values: Iterable[tuple[str, Buffer]]) -> None:
         Insert multiple (key, value) pairs into storage.
         """
         await gather(*starmap(self.set, values))
-        return
 
     @property
     @abstractmethod