Fix incompatibility with the latest typeshed stubs (#103)

`__hash__` in set is now defined as `None`.

Author: JukkaL

sqlalchemy-stubs/sql/base.pyi

@@ -80,4 +80,4 @@ class ColumnSet(util.ordered_column_set[ColumnElement[Any]]):
     # Return type of "__add__" incompatible with supertype "OrderedSet"
     def __add__(self, other: Iterable[ColumnElement[Any]]) -> List[ColumnElement[Any]]: ...  # type: ignore
     def __eq__(self, other: Any) -> bool: ...
-    def __hash__(self) -> int: ...
+    def __hash__(self) -> int: ...  # type: ignore