🐛 fix HasArrayNamespace falsely rejecting ndarray instances on numpy 2

Author: jorenham

src/array_api_typing/_namespace.py

@@ -1,7 +1,7 @@
 __all__ = ("HasArrayNamespace",)
 
 from types import ModuleType
-from typing import Protocol
+from typing import Literal, Protocol
 from typing_extensions import TypeVar
 
 T_co = TypeVar("T_co", covariant=True, default=ModuleType)
@@ -25,4 +25,6 @@ class HasArrayNamespace(Protocol[T_co]):
 
     """
 
-    def __array_namespace__(self, /, *, api_version: str | None = None) -> T_co: ...
+    def __array_namespace__(
+        self, /, *, api_version: Literal["2021.12"] | None = None
+    ) -> T_co: ...