test: ds: update to use new object system

ds-test/numbers.c

@@ -6,6 +6,6 @@ int main(void)
 	b_number *number = b_number_create_float(6.8);
 
 	printf("number=%zd\n", B_NUMBER_IVAL(number));
-	b_number_release(number);
+	b_number_unref(number);
 	return 0;
 }