py: mp_obj_tuple_get: accept any item which can use tuple_getiter

.. such as namedtuple and attrtuple objects.  This is the same
predicate used elsewhere in the file to check for adequate compatibility
between the types.

This was discovered due to crashing `time.time()` on the nrf port.

Closes: #2052

py/objtuple.c

@@ -251,7 +251,8 @@ mp_obj_t mp_obj_new_tuple(size_t n, const mp_obj_t *items) {
 }
 
 void mp_obj_tuple_get(mp_obj_t self_in, size_t *len, mp_obj_t **items) {
-    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_tuple));
+    // type check is done on getiter method to allow tuple, namedtuple, attrtuple
+    mp_check_self(mp_obj_get_type(self_in)->getiter == mp_obj_tuple_getiter);
     mp_obj_tuple_t *self = MP_OBJ_TO_PTR(self_in);
     *len = self->len;
     *items = &self->items[0];