Formatting year_month_day does not work on clang 18.1.0 or earlier, on GCC 13.3 and earlier

[remyjette]

With clang, formatting year_month_day only compiles in Compiler Explorer on trunk. 18.1.0 and earlier do not compile.
If I switch to -stdlib=libc++, it doesn't compile on trunk either.

With GCC, formatting year_month_day only compiles in Compiler Explorer on 14.1 or trunk. 13.3 and earlier do not compile.

https://godbolt.org/z/3ahfo1eKd

Given that the year_month_day type itself is available and fmt supports these compilers I would love to see support.

[vitaut]

We check __cpp_lib_chrono which is technically correct but a PR to enable the use of these chrono types more widely would be welcome.

[vitaut]

Closing as there doesn't seem to be much interest in this but a PR would still be welcome.