util: add missing include for std::set

Change-Id: If18b2f6196e01949b380b41b42ae09e460310ba5

docs/conf.py

@@ -10,7 +10,7 @@ import sys
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
 
 project = 'ndn-cxx: NDN C++ library with eXperimental eXtensions'
-copyright = 'Copyright © 2013-2022 Regents of the University of California.'
+copyright = 'Copyright © 2013-2023 Regents of the University of California.'
 author = 'Named Data Networking Project'
 
 # The short X.Y version.

ndn-cxx/util/logging.hpp

@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,6 +30,7 @@
 
 #include <boost/log/sinks.hpp>
 #include <mutex>
+#include <set>
 #include <unordered_map>
 
 namespace ndn {