Switch to std::filesystem

Drop the dependency on Boost.Filesystem

Change-Id: I5d6f6fe38cd0cf1c6996221188fa63db146dc9f9
diff --git a/tests/tests-pch.hpp b/tests/tests-pch.hpp
index 30e0fdc..c277bcf 100644
--- a/tests/tests-pch.hpp
+++ b/tests/tests-pch.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2024 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,7 +31,7 @@
 
 #include "tests/boost-test.hpp"
 
+#include <filesystem>
 #include <fstream>
-#include <boost/filesystem.hpp>
 
 #endif // NDN_CXX_TESTS_TESTS_PCH_HPP