Fix GCC13 build and enable GCC10 C++11 build

Author: dinomight

include/fmt/base.h

@@ -1060,6 +1060,11 @@ template <typename... Args> constexpr auto count_static_named_args() -> int {
 }
 
 template <typename Char> struct named_arg_info {
+  FMT_CONSTEXPR named_arg_info() : name(nullptr), id(0) {}
+  FMT_CONSTEXPR named_arg_info(const Char* a_name, const int an_id)
+    : name(a_name),
+      id(an_id) {
+  }
   const Char* name;
   int id;
 };