build: require boost >= 1.71.0

Refs: #5276
Change-Id: I287a52dab0212d1ce0da77afb563554214cac68a
diff --git a/tests/unit-tests/dummy-forwarder.hpp b/tests/unit-tests/dummy-forwarder.hpp
index 60e6904..372186e 100644
--- a/tests/unit-tests/dummy-forwarder.hpp
+++ b/tests/unit-tests/dummy-forwarder.hpp
@@ -38,7 +38,7 @@
 class DummyForwarder
 {
 public:
-  DummyForwarder(boost::asio::io_service& io, KeyChain& keyChain);
+  DummyForwarder(boost::asio::io_context& io, KeyChain& keyChain);
 
   Face&
   addFace();
@@ -53,7 +53,7 @@
   removeFaces();
 
 private:
-  boost::asio::io_service& m_io;
+  boost::asio::io_context& m_io;
   KeyChain& m_keyChain;
   std::vector<std::shared_ptr<DummyClientFace>> m_faces;
 };