Fix the array API unique() function

Author: asmeurer

numpy/array_api/_set_functions.py

@@ -12,4 +12,8 @@ def unique(x: Array, /, *, return_counts: bool = False, return_index: bool = Fal
 
     See its docstring for more information.
     """
-    return Array._new(np.unique(x._array, return_counts=return_counts, return_index=return_index, return_inverse=return_inverse))
+    res = np.unique(x._array, return_counts=return_counts,
+                    return_index=return_index, return_inverse=return_inverse)
+    if isinstance(res, tuple):
+        return tuple(Array._new(i) for i in res)
+    return Array._new(res)