[ctypes] Fix argument name (python#14048)

Author: srittau

stdlib/ctypes/__init__.pyi

@@ -41,11 +41,11 @@ _DLLT = TypeVar("_DLLT", bound=CDLL)
 if sys.version_info >= (3, 14):
     @overload
     @deprecated("ctypes.POINTER with string")
-    def POINTER(obj: str) -> type[Any]: ...
+    def POINTER(cls: str) -> type[Any]: ...
     @overload
-    def POINTER(obj: None) -> type[c_void_p]: ...
+    def POINTER(cls: None) -> type[c_void_p]: ...
     @overload
-    def POINTER(obj: type[_CT]) -> type[_Pointer[_CT]]: ...
+    def POINTER(cls: type[_CT]) -> type[_Pointer[_CT]]: ...
     def pointer(obj: _CT) -> _Pointer[_CT]: ...
 
 else: