Fix build with Boost 1.77.

Index: src/network/bufferedconnection.h
--- src/network/bufferedconnection.h.orig
+++ src/network/bufferedconnection.h
@@ -20,6 +20,7 @@
 #ifndef WL_NETWORK_BUFFEREDCONNECTION_H
 #define WL_NETWORK_BUFFEREDCONNECTION_H
 
+#include <map>
 #include <memory>
 #include <mutex>
 #include <thread>
