Add @disjoint_base decorator in the stdlib (#14599)

And fix some other new stubtest finds.

stdlib/_hashlib.pyi

@@ -3,7 +3,7 @@ from _typeshed import ReadableBuffer
 from collections.abc import Callable
 from types import ModuleType
 from typing import AnyStr, Protocol, final, overload, type_check_only
-from typing_extensions import Self, TypeAlias
+from typing_extensions import Self, TypeAlias, disjoint_base
 
 _DigestMod: TypeAlias = str | Callable[[], _HashObject] | ModuleType | None
 
@@ -22,6 +22,7 @@ class _HashObject(Protocol):
     def hexdigest(self) -> str: ...
     def update(self, obj: ReadableBuffer, /) -> None: ...
 
+@disjoint_base
 class HASH:
     @property
     def digest_size(self) -> int: ...