test/source/event: Add missing <type_traits>
diff --git a/test/source/event.cpp b/test/source/event.cpp
index 5f19e81..bfd26c3 100644
--- a/test/source/event.cpp
+++ b/test/source/event.cpp
@@ -8,6 +8,7 @@
 #include <sdeventplus/source/event.hpp>
 #include <sdeventplus/test/sdevent.hpp>
 #include <systemd/sd-event.h>
+#include <type_traits>
 #include <utility>
 
 namespace sdeventplus