fix: c++23 requires utility header for std::unreachable

[russkel]

Fixes this when using GCC C++23:

In file included from /opt/ros/iron/include/xtypes/DynamicType.hpp:21,
                 from /opt/ros/iron/include/xtypes/CollectionType.hpp:21,
                 from /opt/ros/iron/include/xtypes/ArrayType.hpp:21,
                 from /opt/ros/iron/include/xtypes/xtypes.hpp:23,
                 from /home/work/ws/install/nmea0183reader/include/nmea0183reader/definition_plugin.hpp:5,
                 from /home/work/ws/src/nmea0183_lib/include/nmea0183_lib/converters.hpp:6,
                 from /home/work/ws/src/nmea0183_lib/src/xtypes_structs.cpp:4:
/opt/ros/iron/include/xtypes/Assert.hpp:174:12: error: ‘unreachable’ has not been declared in ‘std’
  174 | using std::unreachable;
      |            ^~~~~~~~~~~