message: adapt to new catch2 include paths
diff: #include "fakeit/DefaultFakeit.hpp"
  #include "fakeit/EventHandler.hpp"
  #include "mockutils/to_string.hpp"
  +#if __has_include("catch2/catch.hpp")
  +# include "catch2/catch.hpp"
  +#else
  # include "catch.hpp"
  +#endif
  namespace fakeit {
  