pad3 small optimization

include/spdlog/details/fmt_helper.h

@@ -75,7 +75,7 @@ inline void pad3(int n, fmt::basic_memory_buffer<char, Buffer_Size> &dest)
 
     if (n > 99) // 100-999
     {
-        append_int(n / 100, dest);
+        dest.push_back(static_cast<char>('0' + n / 100));
         pad2(n % 100, dest);
         return;
     }