fix build with clang 13
MODIFY
util/spaceship.h
util/spaceship.h
// Copyright (c) 2018-present The Alive2 Authors.
// Distributed under the MIT license that can be found in the LICENSE file.
-#if defined(__clang__) && __clang_major__ < 13
+#if defined(__clang__) && __clang_major__ < 14
#include <compare>

fix build with clang 13 (#728)