Warning due to XIOS functionality

[jwallwork23]

Since #496, building with XIOS results in a warning:

In file included from /home/joe/software/XIOS/inc/date.hpp:6,
                 from /home/joe/software/neXtSIM-DG/core/test/../../core/src/include/Xios.hpp:14,
                 from /home/joe/software/neXtSIM-DG/core/test/XiosInit_test.cpp:20:
/home/joe/software/XIOS/inc/exception.hpp:64: warning: "INFO" redefined
   64 | #define INFO(x) \
      | 
In file included from /home/joe/software/neXtSIM-DG/lib/doctest/extensions/mpi_sub_comm.h:5,
                 from /home/joe/software/neXtSIM-DG/lib/doctest/extensions/doctest_mpi.h:88,
                 from /home/joe/software/neXtSIM-DG/core/test/XiosInit_test.cpp:17:
/home/joe/software/neXtSIM-DG/lib/doctest/doctest.h:2952: note: this is the location of the previous definition
 2952 | #define INFO(...) DOCTEST_INFO(__VA_ARGS__)
      | 

We should avoid this.

[jwallwork23]

Closed by #588.