[Common] Add IWYU 'keep' pgrama to chrono include

For some reason, my IWYU wants this include to be removed.

emper/Common.hpp

@@ -36,7 +36,7 @@ using func_t = std::function<void()>;
 using WORD = unsigned int;
 
 #ifdef EMPER_STATS
-#include <chrono>
+#include <chrono>	 // IWYU pragma: keep
 #define TIME_NS(code, record_func)                                                         \
 	auto _time_ns_start = std::chrono::high_resolution_clock::now();                         \
 	code;                                                                                    \