message: Fix deprecated-declarations warning with GCC-8.0
  This fixes
diff: @@ -1167,6 +1167,7 @@ namespace detail
  void addToContexts(IContextScope* ptr) { contextState->contexts.push_back(ptr); }
  void popFromContexts() { contextState->contexts.pop_back(); }
  DOCTEST_MSVC_SUPPRESS_WARNING_WITH_PUSH(4996) // std::uncaught_exception is deprecated in C++17
  + DOCTEST_GCC_SUPPRESS_WARNING_WITH_PUSH("-Wdeprecated-declarations")
  void useContextIfExceptionOccurred(IContextScope* ptr) {
  if(std::uncaught_exception()) {
  std::ostringstream stream;
  @@ -1174,6 +1175,7 @@ namespace detail
  contextState->exceptionalContexts.push_back(stream.str());
  }
  }
  + DOCTEST_GCC_SUPPRESS_WARNING_POP
  DOCTEST_MSVC_SUPPRESS_WARNING_POP
  void printSummary();
  