FTBFS in Lunar against doctest 2.4.9

notcurses will FTBFS on recent Lunar, as follows:

In file included from /tmp/autopkgtest.ydP0gv/build.79w/real-tree/src/tests/main.h:9,
                 from /tmp/autopkgtest.ydP0gv/build.79w/real-tree/src/tests/bitmap.cpp:1:
/usr/include/doctest/doctest.h: In instantiation of ‘static void doctest::detail::filldata<T*>::fill(std::ostream*, const T*) [with T = int(const tinfo*, const ncpile*, sprixel*, fbuf*, int, int); std::ostream = std::basic_ostream<char>]’:
/usr/include/doctest/doctest.h:1025:26: required from ‘void doctest::detail::filloss(std::ostream*, const T&) [with T = int (*)(const tinfo*, const ncpile*, sprixel*, fbuf*, int, int); std::ostream = std::basic_ostream<char>]’
/usr/include/doctest/doctest.h:1038:16: required from ‘doctest::String doctest::detail::toStream(const T&) [with T = int (*)(const tinfo*, const ncpile*, sprixel*, fbuf*, int, int)]’
/usr/include/doctest/doctest.h:1046:28: required from ‘static doctest::String doctest::detail::StringMakerBase<true>::convert(const T&) [with T = int (*)(const tinfo*, const ncpile*, sprixel*, fbuf*, int, int)]’
/usr/include/doctest/doctest.h:1079:35: required from ‘doctest::String doctest::toString(const T&) [with T = int (*)(const tinfo*, const ncpile*, sprixel*, fbuf*, int, int); typename detail::types::enable_if<(! detail::types::is_enum<T>::value), bool>::type <anonymous> = true]’
/usr/include/doctest/doctest.h:1476:32: required from ‘doctest::detail::Expression_lhs<L>::operator doctest::detail::Result() [with L = int (*&)(const tinfo*, const ncpile*, sprixel*, fbuf*, int, int)]’
/tmp/autopkgtest.ydP0gv/build.79w/real-tree/src/tests/bitmap.cpp:20:7: required from here
/usr/include/doctest/doctest.h:1166:49: error: invalid conversion from ‘int (*)(const tinfo*, const ncpile*, sprixel*, fbuf*, int, int)’ to ‘const void*’ [-fpermissive]
 1166 | filldata<const void*>::fill(stream, in);

notcurses-3.0.9 fixes this