Revert "update to fmt v12.0.0"

This reverts commit 4dfa2fd.

Author: gastank

engine/lib/fmt/README.md

@@ -71,7 +71,7 @@ class dynamic_arg_list {
  * It can be implicitly converted into `fmt::basic_format_args` for passing
  * into type-erased formatting functions such as `fmt::vformat`.
  */
-FMT_EXPORT template <typename Context> class dynamic_format_arg_store {
+template <typename Context> class dynamic_format_arg_store {
  private:
   using char_type = typename Context::char_type;
 
@@ -212,7 +212,7 @@ FMT_EXPORT template <typename Context> class dynamic_format_arg_store {
   }
 
   /// Returns the number of elements in the store.
-  auto size() const noexcept -> size_t { return data_.size(); }
+  size_t size() const noexcept { return data_.size(); }
 };
 
 FMT_END_NAMESPACE