C++20 support on OpenBSD? (cannot update textproc/libunicode)

Hi,

Recently I found libunicode-0.6.0
(https://github.com/contour-terminal/libunicode) migrates
standard C++20 <format> from libfmt's <fmt/format.h>.

Not only libunicode, contour (X11 terminal) also uses <format> and
I am suffering this migration. clang++-16 looks std::format not supported
or partially/incomplete supported.

Is there any good way to solve this problem? (how about to use llvm-17
in ports?)
--
SASANO Takayoshi (JG1UAA) <uaa@mx5.nisiq.net>