dissect+peek: avoid deprecated ndn-cxx functions

Change-Id: Ibd9f8ad30e315f537d1560db823372af3d58d713
diff --git a/tests/chunks/discover-version.t.cpp b/tests/chunks/discover-version.t.cpp
index 7d18886..a07ecce 100644
--- a/tests/chunks/discover-version.t.cpp
+++ b/tests/chunks/discover-version.t.cpp
@@ -63,8 +63,8 @@
   util::DummyClientFace face{m_io};
   Options opt;
   unique_ptr<DiscoverVersion> discover;
-  optional<Name> discoveredName;
-  optional<uint64_t> discoveredVersion;
+  std::optional<Name> discoveredName;
+  std::optional<uint64_t> discoveredVersion;
   bool isDiscoveryFinished = false;
 };