Avoid deprecated ndn-cxx functions

Change-Id: Idcef8a642affb276581397e869d19534ec776240
diff --git a/tests/identity-management-fixture.cpp b/tests/identity-management-fixture.cpp
index c4a4590..254da23 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) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2022 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -115,7 +115,7 @@
   certificate.setFreshnessPeriod(1_h);
 
   // set content
-  certificate.setContent(key.getPublicKey().data(), key.getPublicKey().size());
+  certificate.setContent(key.getPublicKey());
 
   // set signature-info
   SignatureInfo info;