add a missing header

dietmarkuehl · dietmarkuehl · commit 79912566f8b8 · 2025-04-21T21:05:47.000-04:00
diff --git a/examples/intro-timer.hpp b/examples/intro-timer.hpp
@@ -7,6 +7,7 @@
 #define INCLUDED_EXAMPLES_INTRO_TIMER
 
 #include <beman/execution/execution.hpp>
+#include <chrono>
 #include <queue>
 #include <thread>
 #include <tuple>
