tests: avoid use of deprecated default SigningInfo

refs #4804

Change-Id: I32db316bbaca89fb92ec4b70568d0ff7fcd3423b
diff --git a/tests/test-common.hpp b/tests/test-common.hpp
index c5c12bc..3139ef9 100644
--- a/tests/test-common.hpp
+++ b/tests/test-common.hpp
@@ -113,7 +113,7 @@
  */
 ndn::PrefixAnnouncement
 signPrefixAnn(ndn::PrefixAnnouncement&& pa, ndn::KeyChain& keyChain,
-              const ndn::security::SigningInfo& si = ndn::KeyChain::getDefaultSigningInfo(),
+              const ndn::security::SigningInfo& si = ndn::security::SigningInfo(),
               optional<uint64_t> version = nullopt);
 
 } // namespace tests