Include <exception> for std::terminate

[francoisk]

The header checked_result_operations.hpp calls std::terminate which is in <exception> but the latter is not included, causing compilation failures with clang 18 and libc++:

include/boost/safe_numerics/checked_result_operations.hpp:40:14: error: no member named 'terminate' in namespace 'std'; did you mean 'template'?
   40 |         std::terminate();
      |         ~~~~~^~~~~~~~~
      |              template