fmt issues on Ubuntu 24

[mathieu-celerier]

This error came up to me when compiling my "mc_mujoco" fork which uses this repo as a submodule.

[mathieu-celerier]

Although the proposed fix in #9 seems to solve some issues, there is still issues related to fmt and Eigen objects.
Following is an error obtained while compiling mc_mujoco:

/usr/include/fmt/core.h: In instantiation of ‘constexpr fmt::v9::detail::value<Context> fmt::v9::detail::make_value(T&&) [with Context = fmt::v9::basic_format_context<fmt::v9::appender, char>; T = Eigen::Matrix<double, 3, 1>&]’:
/usr/include/fmt/core.h:1777:29:   required from ‘constexpr fmt::v9::detail::value<Context> fmt::v9::detail::make_arg(T&&) [with bool IS_PACKED = true; Context = fmt::v9::basic_format_context<fmt::v9::appender, char>; fmt::v9::detail::type <anonymous> = fmt::v9::detail::type::custom_type; T = Eigen::Matrix<double, 3, 1>&; typename std::enable_if<IS_PACKED, int>::type <anonymous> = 0]’
/usr/include/fmt/core.h:1901:77:   required from ‘constexpr fmt::v9::format_arg_store<Context, Args>::format_arg_store(T&& ...) [with T = {Eigen::Matrix<double, 3, 1, 0, 3, 1>&}; Context = fmt::v9::basic_format_context<fmt::v9::appender, char>; Args = {Eigen::Matrix<double, 3, 1, 0, 3, 1>}]’
/usr/include/fmt/core.h:1918:31:   required from ‘constexpr fmt::v9::format_arg_store<Context, typename std::remove_cv<typename std::remove_reference<Args>::type>::type ...> fmt::v9::make_format_args(Args&& ...) [with Context = fmt::v9::basic_format_context<fmt::v9::appender, char>; Args = {Eigen::Matrix<double, 3, 1, 0, 3, 1>&}]’
/usr/include/fmt/core.h:3206:44:   required from ‘std::string fmt::v9::format(fmt::v9::format_string<T ...>, T&& ...) [with T = {Eigen::Matrix<double, 3, 1, 0, 3, 1>&}; std::string = std::__cxx11::basic_string<char>; fmt::v9::format_string<T ...> = fmt::v9::basic_format_string<char, Eigen::Matrix<double, 3, 1, 0, 3, 1>&>]’
/home/mathieu/devel/mc_rtc/src/mc_mujoco/ext/mc_rtc-imgui/widgets/form/widgets.h:583:30:   required from ‘std::string mc_rtc::imgui::form::SimpleInput<DataT>::value() [with DataT = Eigen::Matrix<double, 3, 1>; std::string = std::__cxx11::basic_string<char>]’
/home/mathieu/devel/mc_rtc/src/mc_mujoco/ext/mc_rtc-imgui/widgets/form/widgets.h:580:15:   required from here
/usr/include/fmt/core.h:1757:7: error: static assertion failed: Cannot format an argument. To make type T formattable provide a formatter<T> specialization: https://fmt.dev/latest/api.html#udt
 1757 |       formattable,
      |       ^~~~~~~~~~~
/usr/include/fmt/core.h:1757:7: note: ‘formattable’ evaluates to false