Switch to Face::getIoContext()

Change-Id: I34bb49dc96e91e6f0ff8f9be9185949df3a9739c
diff --git a/tools/ndns-dig.cpp b/tools/ndns-dig.cpp
index 88340d9..0bb9d0b 100644
--- a/tools/ndns-dig.cpp
+++ b/tools/ndns-dig.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2020, Regents of the University of California.
+ * Copyright (c) 2014-2024, Regents of the University of California.
  *
  * This file is part of NDNS (Named Data Networking Domain Name Service).
  * See AUTHORS.md for complete list of NDNS authors and contributors.
@@ -86,7 +86,7 @@
   void
   stop()
   {
-    m_face.getIoService().stop();
+    m_face.getIoContext().stop();
     NDNS_LOG_TRACE("application stops.");
   }