Appender doesn't work on wide strings

include/spdlog/logger.h

@@ -394,12 +394,8 @@ protected:
         {
             // format to wmemory_buffer and convert to utf8
             wmemory_buf_t wbuf;
-#    ifdef SPDLOG_USE_STD_FORMAT
             fmt_lib::vformat_to(
                 std::back_inserter(wbuf), fmt, fmt_lib::make_format_args<fmt_lib::wformat_context>(std::forward<Args>(args)...));
-#    else
-            fmt::vformat_to(fmt::appender(wbuf), fmt, fmt::make_format_args<fmt::wformat_context>(std::forward<Args>(args)...));
-#    endif
 
             memory_buf_t buf;
             details::os::wstr_to_utf8buf(wstring_view_t(wbuf.data(), wbuf.size()), buf);