To avoid warnings like:
In file included from /usr/include/c++/13/regex:50,
from ../../components/lua/yamlloader.cpp:6:
In constructor 'std::function<_Res(_ArgTypes ...)>::function(std::function<_Res(_ArgTypes ...)>&&) [with _Res = bool; _ArgTypes = {char}]',
inlined from 'std::__detail::_State<_Char_type>::_State(std::__detail::_State<_Char_type>&&) [with _Char_type = char]' at /usr/include/c++/13/bits/regex_automaton.h:149:4,
inlined from 'std::__detail::_StateIdT std::__detail::_NFA<_TraitsT>::_M_insert_subexpr_begin() [with _TraitsT = std::__cxx11::regex_traits<char>]' at /usr/include/c++/13/bits/regex_automaton.h:281:24:
/usr/include/c++/13/bits/std_function.h:405:42: error: '*(std::function<bool(char)>*)((char*)&__tmp + offsetof(std::__detail::_StateT, std::__detail::_State<char>::<unnamed>.std::__detail::_State_base::<unnamed>)).std::function<bool(char)>::_M_invoker' may be used uninitialized [-Werror=maybe-uninitialized]
405 | : _Function_base(), _M_invoker(__x._M_invoker)
| ~~~~^~~~~~~~~~
In file included from /usr/include/c++/13/regex:65:
/usr/include/c++/13/bits/regex_automaton.h: In member function 'std::__detail::_StateIdT std::__detail::_NFA<_TraitsT>::_M_insert_subexpr_begin() [with _TraitsT = std::__cxx11::regex_traits<char>]':
/usr/include/c++/13/bits/regex_automaton.h:279:17: note: '__tmp' declared here
279 | _StateT __tmp(_S_opcode_subexpr_begin);
| ^~~~~
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105562.
We've not used AppVeyor for years.
If we started again, it'd use a different version of Boost and that aspect would need redoing anyway.
Everything else that was AppVeyor-specific is something we've got away without in GitLab CI so can't have been especially important.
