Update Catch2 to v3

tests/timed_events.cpp

@@ -1,21 +1,7 @@
-#include "catch.hpp"
+#include "catch2/catch_test_macros.hpp"
 
 #include <utils/timed_events.hpp>
 
-/**
- * Let Catch know how to display std::chrono::duration values
- */
-namespace Catch
-{
-  template<typename Rep, typename Period> struct StringMaker<std::chrono::duration<Rep, Period>>
-  {
-    static std::string convert(const std::chrono::duration<Rep, Period>& value)
-    {
-      return  std::to_string(std::chrono::duration_cast<std::chrono::milliseconds>(value).count()) + "ms";
-    }
-  };
-}
-
 /**
  * TODO, use a mock clock instead of relying on the real time with a sleep:
  * it’s unreliable on heavy load.