tests: fix compilation with latest ndn-cxx

Change-Id: I32579dd584efee508c862b3d5f2f1bdad7487bab
diff --git a/tests/identity-management-fixture.cpp b/tests/identity-management-fixture.cpp
index f545710..4751b99 100644
--- a/tests/identity-management-fixture.cpp
+++ b/tests/identity-management-fixture.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
 /*
- * Copyright (c) 2012-2022 University of California, Los Angeles
+ * Copyright (c) 2012-2023 University of California, Los Angeles
  *
  * This file is part of ChronoSync, synchronization library for distributed realtime
  * applications for NDN.
@@ -53,7 +53,7 @@
 bool
 IdentityManagementFixture::saveIdentityCertificate(const Name& identity, const std::string& filename, bool wantAdd)
 {
-  ndn::security::v2::Certificate cert;
+  ndn::security::Certificate cert;
   try {
     cert = m_keyChain.getPib().getIdentity(identity).getDefaultKey().getDefaultCertificate();
   }