Revert "Updated bundled fmt to version 10.0.0"

This reverts commit 62e55e7a7f.

src/bundled_fmtlib_format.cpp

@@ -9,13 +9,14 @@
 #if !defined(SPDLOG_FMT_EXTERNAL) && !defined(SPDLOG_USE_STD_FORMAT)
 
 #include <spdlog/fmt/bundled/format-inl.h>
+
 FMT_BEGIN_NAMESPACE
 namespace detail {
 
 template FMT_API auto dragonbox::to_decimal(float x) noexcept
--> dragonbox::decimal_fp<float>;
+    -> dragonbox::decimal_fp<float>;
 template FMT_API auto dragonbox::to_decimal(double x) noexcept
--> dragonbox::decimal_fp<double>;
+    -> dragonbox::decimal_fp<double>;
 
 #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
 template FMT_API locale_ref::locale_ref(const std::locale& loc);
@@ -25,23 +26,27 @@ template FMT_API auto locale_ref::get<std::locale>() const -> std::locale;
 // Explicit instantiations for char.
 
 template FMT_API auto thousands_sep_impl(locale_ref)
--> thousands_sep_result<char>;
+    -> thousands_sep_result<char>;
 template FMT_API auto decimal_point_impl(locale_ref) -> char;
 
 template FMT_API void buffer<char>::append(const char*, const char*);
 
+// DEPRECATED!
+// There is no correspondent extern template in format.h because of
+// incompatibility between clang and gcc (#2377).
 template FMT_API void vformat_to(buffer<char>&, string_view,
-                                 typename vformat_args<>::type, locale_ref);
+    basic_format_args<FMT_BUFFER_CONTEXT(char)>,
+    locale_ref);
 
 // Explicit instantiations for wchar_t.
 
 template FMT_API auto thousands_sep_impl(locale_ref)
--> thousands_sep_result<wchar_t>;
+    -> thousands_sep_result<wchar_t>;
 template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;
 
 template FMT_API void buffer<wchar_t>::append(const wchar_t*, const wchar_t*);
 
-}  // namespace detail  
+}  // namespace detail
 FMT_END_NAMESPACE
 
 #endif // !SPDLOG_FMT_EXTERNAL