Replace fmt::localtime with std::localtime

fmt::localtime was deprecated in fmt 11.2.0 and removed in fmt 12.0.0.
Replace with std::localtime from <ctime> which is already included
transitively.

Fixes #2456
Signed-off-by: Kefu Chai <tchaikov@gmail.com>

Author: tchaikov

src/logging.cpp

@@ -27,8 +27,9 @@ void logger_t::generate_common_prefix(std::string *str,
                                       fmt::text_style const &ts,
                                       char const *prefix) const
 {
+    auto const now = std::time(nullptr);
     *str += fmt::format("{:%Y-%m-%d %H:%M:%S}  ",
-                        fmt::localtime(std::time(nullptr)));
+                        *std::localtime(&now));
 
     if (m_current_level == log_level::debug) {
         *str += fmt::format(ts, "[{:02d}] ", this_thread_num);