Build failed due to missing include

My CI [failed](https://github.com/keyehzy/manybody/actions/runs/21237220376/job/61107609833) due to a missing include in rapidcheck/include/rapidcheck/Maybe.h.

Here is the patch to fix it.

```diff
@@ -1,7 +1,8 @@
 #pragma once
 
-#include <type_traits>
+#include <cstdint>
 #include <iostream>
+#include <type_traits>
 
 #include "rapidcheck/Nothing.h"
 ```
