Reduce unnecessary inclusions of `detail/common.hpp`

Change-Id: I79dcd05297594ccd4489d8cddddb879655373cc0
diff --git a/tests/unit/net/dns.t.cpp b/tests/unit/net/dns.t.cpp
index 17c5438..c1e8679 100644
--- a/tests/unit/net/dns.t.cpp
+++ b/tests/unit/net/dns.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2023 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).
  *
@@ -20,6 +20,7 @@
  */
 
 #include "ndn-cxx/net/dns.hpp"
+#include "ndn-cxx/detail/common.hpp"
 
 #include "tests/boost-test.hpp"
 #include "tests/unit/net/network-configuration-detector.hpp"