[Bug libstdc++/108062] Test spdlog c++20 std::format

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108062

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I tried to test this but my cmake is not new enough:
  Target "example" requires the language dialect "CXX20" , but CMake does not