Slim down `common.hpp`

Change-Id: Ic9843a1b9ffc5b5b1fa6062c8250ba28c6aaa898
diff --git a/core/program-options-ext.hpp b/core/program-options-ext.hpp
index 16b4e41..a505ece 100644
--- a/core/program-options-ext.hpp
+++ b/core/program-options-ext.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2024,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -28,6 +28,7 @@
 
 #include <ndn-cxx/name.hpp>
 #include <boost/program_options/value_semantic.hpp>
+#include <vector>
 
 namespace ndn {